Too mired in mere survival to consider changes that would makes us happier. We still practice the norms of tribal living, the norms which made us effective at violence. These norms were enacted through more violence of course and so now when the norms are no longer needed people aren't interested in discarding them unless they can't manage to find some happiness in this society. IOW, the people who either really do have a bit of something wrong with them or perhaps a few who are simply bored but... I think the later is a small minority.