It… isn’t that simple.
Ever hear of the prisoner’s dilemma?
two prisoners are caught by the police and given the chance at a reduced sentence if they rat on their partner. Each perp needs to decide whether he wants to try for the reduced sentence. No matter what his partner does, HE would be better off to rat on his partner (his sentence is increased if he stays silent while his partner rats on him.), yet both perps are better off if NEITHER of them rat on each other.
This game is, in a sense, a larger version of that dillemma.
Some people spend their academic careers studying prisoner’s dilemma and other related hypotheticals in game theory. It’s hardly as simple as saying, “Anyone who isn’t an idiot would choose not to rat on their partner.”