Humans have 3 inch chimp brains. The expectations on those poor brains are too high. Its like expecting dogs to one day figure out how to run a mcdonalds. We do what we can. Theory of Bounded Rationality applies. The vanity part has to do with Status Signaling. And status signaling is one of few know hacks that work at population scale in keeping all the different chimps together. Granted the status signalers some times get carried away and forget what its purpose is. See Theory of the Leisure Class.