What made the world less overtly-violent after WWII?

When I learn about WWI and II, it seems like political asinations were the norm and people like Stalin would wipe out millions of his own men because he was paranoid. In my whole lifetime, I've not seen many things that equal the ways of that generation. There have been things like 9-11, but on a large scale I do not hear about many violent movements overtaking entire continents. Also, your average man of the past thirty years does not seem like the men that were alive in WWII times. Men now just text all day and pick up and dump women and snort coke. No one fights for anything. What changed? I can tell the world is much more peaceful today, although people are lame, but why?