Yes we can't rely only in bitcoin cause the value of bitcoin is not stable and like today the price of btc and other crypto is bad and some crypto addicts leave crypto industry, better to make btc as your part time not a main source of income and you should have your main job like physical job or much better if you own business that can sustained you daily living.
I'm sure the bear market has really teach those who rely on crypto as their means to survived. The market is very unstable and there's no way that someone will look at it like a stable job. 2017 is different and so is 2018. If you think that you can make lots of money just like 2017 then you're totally wrong. That's why it's better to save your earnings in crypto because we really don't know how far can it go to provide us with the needed money to bring food for our family (if you considering crypto as your main source of income).