My wife and I consider the kids' college housing costs to be the one major mistake we made in our lives.
Before the oldest headed off to college we had decided that we were going to foot the bill for their four year undergraduate degree at the University of Minnesota. A lot of our friends suggested it was a bad idea, for a variety of reasons, including the proverbial "no skin the game" argument. But we ultimately decided that since we could afford to pay that bill, and because if we didn't they were likely looking at student loan debt that would sabotage things like houses, cars, families, etc..., for not just years but decades, it was our chance to give them a leg up over what many of their contemporaries faced coming out of college.
We don't regret that decision one bit, especially when I read all the horror stories now of kids and their debt. What we do regret is not proceeding with a plan that I knew was a great idea but I just couldn't pull the trigger on, and that was buying a condominium in Minneapolis/St. Paul and basically making the girls live there instead of in the dorms and apartments they ultimately chose. I would have been building equity instead of U of M buildings. Bad decision.