No brofist here.
Marrying the right girl makes it all worth it. I've seen one or two ugly marriages; it isn't pretty, and neither is the train wreck at the end.
But looking at my grandparents (both sides) and my own mother and father, finding the right girl really does make it worth it.
Many people just don't invest the time into finding the right person, or into making it work. Is it possible that the nice girl you met in the library and have known for four years, been together for another three, and started living together after that will turn into a psycho-bitch after years of being married to you? Maybe (at which point I'd wonder what I did to fuck her up *that* much). But I'd expect psycho tendencies to show up long before then, and hopefully before legally binding contracts have come into play. And I'd expect the probability of her sleeping around behind my back to be far less than that of some random chick I met in a bar,nightclub, or on the beach.
Then again, being highly educated and relatively affluent doesn't hurt either.