The question of whether striving and acquiring make us happy will probably always be a teaser and conversation starter. But Virginia Postrel suggests that the attractions of the trappings that go with success are worthy because they incite the actions that go with progress.
What about procreation? In past times, natural lust was thought to take care of that. But ever since that link has become an option, we can ask about the priors that would-be parents start with. Perhaps crazy optimism among the young is a good thing. Julian Simon would probably agree. Pessimism and caution in old age also seem to be useful adaptations. It is pessimism among the young that has no easy explanation -- and that is seemingly rare.