I can't really see any cryptocurrency being an efficient source of income. The price fluctuates way too much. One day you could have 50,000$ in a certain coin and the next day you're flat broke and can't pay bills. Of course it would work if you were very, very good at predicting the price of the coin so you can exchange when you feel the price way going down, or get more Bitcoin when you think it is going to go up, but you'd already most likely been in luck for a stable job if you were good enough at that.