[H1N1]

If you haven't, I'd recommend reading 'Principles' by Ray Dalio (free pdf at first link on Google), who started Bridgewater and has obviously enjoyed huge financial success. He thinks quite deeply about this, and about what our motivations should be. Fundamentally though, his view is that he isn't noticeably happier for having a lot of money, because buying things isn't how he derives joy. Since most of his pleasures are not material, making a lot of money hasn't actually significantly increased his happiness. He says quite openly that if it wasn't for the fact that he really loves what he does, he wouldn't bother, because the money/lifestyle is not a motivating factor. Of course, it's easy to say that when you're in the Forbes 400 or whatever it is, but he seems sincere, and comes from nothing so has the perspective to know what the alternative is, at least.