Well, everyone who gets married is irrationally overoptimistic about the likelihood of divorce.
Are they? One puzzle is that statistics show divorce to be relatively uncommon, at least for mid-to-upper class folks. So perhaps the moral hazard problem isn't quite as terrible as it looks at first glance, given this institutional framework. Maybe judges don't really ignore pre-nup agreements in many cases; maybe the tradcons are right and "character", "morality" etc. work well enough as a precommitment mechanism. Who knows. Of course the probabilities are still bad enough that reasonable guys arguably should not marry; the question is why they aren't worse.
Perhaps not everyone, but definitely most. Most people, from my experience, view divorce as 10% likely. The 'relatively uncommon' statistics you reference above are on the order of 50%. That's a pretty big gap.
Dalrock writes an interesting article related to Dr. Helen Smith's book the Marriage Strike. I really have to bump it up on my too rapidly growing reading list. (^_^)