I echo what @inuke has said. Articles on Hive down generate any income after 7 days. Maybe content writing outside high for any high quality requirement can pay close to 20 dollars per hour. 

These days there are a few high skill based jobs available that can pay 30$ per hour. If that happens and if the income is regular, people can easily make 120$ in 4 hours a day. So even with a full time job as backup, it should be possible but as you said it has to be very hard work.