I've known this all along but I think that many players don't take it into account as much as they should. I decided to make this post bec just the other day, playing modest stakes limit, someone asked another player about the weekly home game that he played in (no pro has any chance of being invited). The size of the game astonished me, it's pretty huge, and the amounts won and lost are very large. But here he was, obv w/ a poker jones, playing what is for him, for pennies.
Whenever you get tilted or enraged by a stupid play that any sensible player would not make, think that you've gotten run over by a fish that doesn't have any business playing for real money, you might consider the above. The stakes most of us play for are, for many of these ppl, meaningless and keeping that in mind might help w/ perspective.