Actually there isn't any interest in Steem Power. Sure it builds over time, but this is balanced out by the dilution of Steem as more and more Steem are coming into life everyday. But yeah, there's still room for the market cap to grow so I guess you can consider it an interest atm. I consider myself quite lucky for good upvotes.. so it's time to distribute it to newcomers. It'll take time.. heck Steemit's only a few weeks old ever since the public influx from 4th July.