Bitcoin can be a main source of income or not that depend on how you make money with bitcoin . If you are a trader, bitcoin will be your main
source of income, if you only make money with bitcoin by bounty or airdrop, bitcoin will not be your main source of income in the long run .because
you can not do this job forever and the bitcoin price is always changing.
But i think that no one can claim that he can earn a stable income from bitcoin, i think that it is really difficult to predict the bitcoin price, and that is way it is not possible for us to make a stable income from bitcoin investment or trading, to me i think that we cannot cosider bitcoin as our main source of income, but it can only be cosider as our side business from where we can expect to make some good income if the price goes up.