Hmm...statistically 2/3 of Americans are overweight or obese. Does that mean that since I live in the US that I have a 66% chance of being fat? Well, that's one way to look at it but it is misleading. I have a choice in how I conduct my life, and I can make choices that almost entirely eliminate the "chance" that I will be overweight. A 50% divorce rate doesn't mean marriage is a crapshoot.
A pre-nup is a bit like high blood pressure medication - you can be overweight and sedentary and take pills, or you can eat right and exercise and prevent the high blood pressure in the first place. Proper diet and exercise won't guarantee you won't develop high blood pressure, but they greatly reduce the risk. The problem is, diet and exercise are hard-ass work and most people would rather take the pill. Same with marriage - there are things you can do to keep it healthy, but most people don't want to do them because they're hard-ass work. They wait too long to resolve issues and by the time they try it is too late. An ounce of prevention is worth a pound of cure. There are hundreds of books available on how to make a happy, healthy marriage - it's not exactly esoteric information. Should those strategies fail, there are thousands of marriage and family counselors available to speak to. Anecdotes are not data, but of the divorcees I am close to, not a single one attended more than a handful therapy sessions before calling it quits - and most never even tried it.
The "post-nup" we agreed to is this: if ever in the future one or both of us wants a divorce we will attend 24 months of couples and individual counseling prior to the dissolution. If either refuses, the other gets 100% of the assets (excluding personal effects and individual retirement accounts). If both refuse, our estate is to be liquidated and donated to charity.
I don't know what the divorce rate is of couples that have completed 24 months of therapy sessions, but I suspect it is much lower than 50% (though it is undoubtedly not 0%, nothing is a guarantee). Plus, rather than a standard pre-nup that sends the message "Hey, we might divorce someday, so let's prepare for it now", our version sends the message "Hey, we might have a rough time someday, so let's prepare to weather that storm together and give ourselves the best chance we can of succeeding as a couple."
It's not a perfect solution by any means, but I believe it is more conducive to developing a healthy partnership than a standard what's-mine-is-mine pre-nup. "You cannot simultaneously prevent and prepare for war'" and all that...