To explain why Bitcoin isn't the coin of the future anymore, I have to go over some basic principles. Skip them if you're a guru.

# Bitcoin fundamentals.
Bitcoin like other cryptocurrencies is secure because it's based on a blockchain. A transaction log of every transaction performed on the network. For our purposes lets simplify what that blockchain looks like for a transaction:

Joe, sends 30 bitcoins to Tony on 01 January 2018 at 1300H
This might be written to the blockchain as: JOE_30_TONY_01JAN2018_1300

That way, Joes account is 30 Bitcoin less than what he started and Tony’s is 30 more. The next transaction is basically appended to the last and so it goes.

Where is the blockchain stored? Well it's not stored like the rest of the internet on a central web server like Amazon, it's stored in a live document, kept alive by hundreds of thousands of computers working together. 

The computers are running software which is connected to the internet and writes the blockchain over and over (This is called mining). Because all of the computers are agreeing on the blockchain, and confirming with each other the validity of it, it basically becomes incorruptible, as there isn't any way to rewrite the blockchain as it stands. Somewhere in the blockchain, every single bitcoin is accounted for.

The computers mining bitcoin are incentivised to do so by awarding bitcoin at regular intervals. The bitcoin is rewarded based on how much a computer contributes to the overall computing power. So if there are only two computers mining Bitcoin in total, owned by Matt and Didier, their combined computing power is called the network hash rate. If Matt has a computer that has 10 megahertz(MH/S) (A measure of computing power) and Didier has a computer that has 10MH/S, then they can both expect to get an equal share of the bitcoin awarded, and the network hash rate is 20MH/S.

However the Bitcoin network hasn't had a hash rate that small since it was made. What happened, as you might imagine, is that once people saw that you could mine Bitcoins using your home computer and basically get free money, everybody jumped on board. People started getting more powerful computers for this purpose alone, which led to a major shift in technology. A normal computer has different types of processing power: the main chip (Intel Pentium etc, called  CPU), RAM (Random access memory) and the Graphics card (Graphics Processing Unit or GPU. Originally, Bitcoin was mined using the CPU and RAM. But a new method was developed which allowed coins to be mined at a much higher rate using the GPU. This kept everyone happy for a while before someone decided to make a machine which does nothing else but mine bitcoin (ASIC). 

Whilst original mining rigs were based on your average computer components and could be recycled to do other things apart from Bitcoin, ASIC machines can only mine bitcoin and nothing else. This is an important factor later on.

Once popularity of Bitcoin started to grow between $30USD and $100USD during the Cyprian financial crisis in 2013, mining bitcoin became a lot more profitable. And we started to see much more substantial and complex investment in bitcoin mining, with people  converting entire buildings into bitcoin mining warehouses. 
http://money.cnn.com/2013/03/28/investing/bitcoin-cyprus/index.html
Surging to recent prices of up to $20k USD.

# The cost of mining
This brings us to another point, what does the computer the miners are contributing? Writing the blockchain over and over sounds like a very simple task. So why does it take so much computing power? Well, because the amount of computing power has no limit, the same amount of bitcoin will be awarded to miners irrespective of how much the total network hash rate is. Therefore, the more powerful your computer, the higher the rewards you can expect, driving competition.

Miners now calculate mining profitability based on a number of factors: 
1. How powerful their computer is(MH/S or hashrate)
2. What share for mining they can expect to get (Based on what percentage they contribute to the overall network hashrate)
3. How much electricity they will use to mine
4. The cost of that electricity
5. The cost of their mining equipment (and how long it would take to pay it back)
6. The current and future value of Bitcoin.

If it costs $30 per month to run a mining rig, but we can only expect to get $32USD worth of bitcoin in that time, it doesn't seem worth it. But if that $32USD worth of bitcoin then becomes worth $100 in two weeks, then mining is profitable.

For those of you who own businesses, it's worthwhile checking your electricity usage and if any of your staff have hidden mining rigs in your workplace. Free power substantially increases the profitability of mining and is increasingly commonplace.

To give perspective regarding hashrate, a basic computer costing about $1000 USD, would expect to have a hash rate of about 20-30 MH/S. The overall network hashrate is 16,600,000,000,000 MH/s.

# Electricity & climate change
The amount of power bitcoin consumes is astronomical. The website digiconomist.net keeps tabs on the power consumption. At the time of writing, it’s expected that the annual electrical usage of the bitcoin network is 41.79TWh, which makes it on par to the power consumption of the country of New Zealand. Costing about $2billion dollars to run annually. (https://digiconomist.net/bitcoin-energy-consumption)

What exactly is that money buying? The mining is what underpins the network. So every time a transaction is processed, it’s enabled by the miners who are in turned rewarded in Bitcoin(which cost them electricity to mine). Thus there is a direct relationship with spending money on electricity and adding value to Bitcoin. 

Take into account the global emphasis on carbon emissions and climate change. Governments are facing increasing pressure to either reduce electricity usage, or increase renewable energy. Bitcoin still hasn't been considered at large by governments worldwide in financial terms, let alone environmentally. It's increasingly unlikely that a government will sign a climate change agreement with one hand and then be seen to invest or support a financial system that is a major user of electricity. Especially one which is so wasteful.

The argument exists that decentralised financial cryptocurrency systems are here to stay, and also that normal financial systems still require massive amounts of energy to be maintained. So why are we so harsh on Bitcoin? Because, it’s old technology that whist it was ground-breaking at the time, has been usurped by new more effective, less wasteful alternatives.

# Utility
Emerging cryptocurrencies are improving on the bitcoin technology. Instead of simply writing the blockchain, they using the processing power to enable other technologies. 

The bitcoin mining software is basically just burning electricity to perform the relatively simple task of maintaining the blockchain. However alternative coins (altcoins) are addressing this wastefulness by adding secondary utility to the mining activity. Whilst they still maintain the blockchain they also perform other duties, such as allowing users to create smart contracts (Ethereum), provide online storage (Siacoin, Storj) or even enable hosting programming languages through a decentralised web(NEO, ETP). In this manner, the electricity spent isn't merely burnt up for the purpose of writing the blockchain, instead it's used to power networks which give the world some utility.

Imagine spending the equivalent of the electricity usage of New Zealand on powering a new internet. One which couldn’t be controlled by any government.

# Mining equipment commitment
Should you rip your money out of bitcoin immediately? Well, consider the huge amounts of investment put into Bitcoin mining. The ASIC machines that can only mine bitcoin and nothing else. Bitcoin will still remain a safe place to store intrinsic value, but that time is limited. We would expect that at some point, a new and improved coin will introduce features which Bitcoin currently lacks, in fact there are many out there already. Which one it will be is anyone’s guess. But my bet is that it would eventually be one that provides a high level of utility. 

Bitcoin miners whose mining rigs aren’t locked only to bitcoin can very easily start mining alternative cryptocurrencies. Thus, if another coin is showing great profitability, there is immediate incentive to swap. 

If all miners were to stop mining bitcoin, transactions are no longer possible, the blockchain is essentially lost and bitcoin dead. Whilst this is an unlikely scenario due to the heavy investment in bitcoin specific mining equipment, it is important to know the risks.

# Reward lifecycle
Bitcoin has also been set at 21million coins. Therefore, once those 21 million coins have been mined, the incentive for miners to continue mining bitcoin is diminished. The incentive is replaced by miners getting rewarded for processing transactions on the network. This is expected to be a much smaller reward and less likely to be incentive enough to mine, though this is still speculative. It is suggested that by the time this happens, the computational power required to process the transaction will be insignificantly small. There is a great article about this here:
https://news.bitcoin.com/what-happens-bitcoin-miners-all-coins-mined/or

# Majority rules & lack of a single standout competitor
At the moment Bitcoin is the major coin by market share, instilling a sense of security in users. This security is thinly veiled. Should another cryptocurrency show strength and stability whilst bitcoin starts to slide, those holding bitcoin will exhibit no loyalty towards holding a dying currency. They'll dump it for the next most stable platform. Those holding Bitcoin would need to be watching the market constantly or have set sell orders at lower prices. 

# So how to choose the bitcoin replacement? 
The utility of Ethereum was immediately evident. Users quickly started realising this and invested in it. This improved mining incentivisation and the network received a healthy dose of investment. The basic principle for cryptocurrency investment is to keep abreast of emerging technologies so that you can invest in the ones that you perceive to have the most utility in the world ahead, and pull out of the ones having their utility replaced.

So, in summary, Bitcoin might have been the coin of the future, but that future has now past.  

If you have any suggestions or see fit to correct anything, or just say hey, please do so!