It is possible, but only if you have the necessary skills. But I don't recommend you completely abandon official work. No one knows what will happen with bitcoin in the future. You risk to remain without money and pensions. You will agree with me it is very risky.
Exactly, it is important to secure our future and to have a passive income monthly for us to survive. Talking about the money we possibly get from bitcoin isn't totally good enough if you are just in the lower rank, but in the higher there is a chance. We can't still rely on bitcoin at all, even though we can make money from here but still we find ways in addition to our income.
Absolutely, no serious mind will leave his full time job for Bitcoin because that should be the main source of income whereas Bitcoin and other freelance jobs become secondary source of income.