I don't know what the right amount is, but with the numbers being where they are, it just seems like doing any of the jobs that are considered socially useful (doctor/nurse/policeman/research/etc) is simply too big a sacrifice if you have the choice.

You might be right about the prisoner's dilemma: if you are an engineer and you get an offer from the cure for cancer research group, vs potentially 7 figures in a few years, it's going to be awfully hard to save humanity.