What do you mean by a bitcoin full time job ? If you mean trading so my answer is no because trading is risky and one should have another source of income.
If you mean to create a bitcoin project, it depends on the idea if it good and will go viral or not
you can use sign campaign + trading, you can earn not only from bitcoin, if you focus at online earning you will find VLOG, youtube ads, google ads etc.
if you want to leave your realjob and focus at internet, my suggest for you, you must have capital to start it because sometimes in first month you can't get eanything.