Likely people who play poker for a living have this factored into their play. For example, if you play 3/6 and you know you can consistently make 4BB/hour (a good goal over time) then you are making $24 an hour. At 5/10 you're making $40 an hour.

High level players generally have such a huge bankroll that unless they have a bad weekend they can walk into Vegas or AC and walk out with a couple of grand over a weekend. Reading Phil Gordon's books he would enter high level tourneys and get knocked out, and then go and play cash games in the same casino to win his money back .

I think if you're playing to actually pay your bills the game changes quite a bit. If it were me I would have lots of money put aside each month in case of a bad run so that bills could get paid. Your bankroll is just that, your bankroll - not your source of income.