If they can afford it, they do. If the kid wastes the opportunity and drops out or gets kicked out, that's something the kid will have to deal with.
Parents don't owe their kids a college education at any college they want to go to. If I had a kid with this problem I certainly wouldn't send them to Brown.
As expensive as college is these days, very few people can really "afford" it anyway. Personally, I will absolutely make every sacrifice in that area for my child. But not because I owe it to him, or because I love him more than other people love their kids. I home school too, for similar reasons.
You know though, I cannot say that my financial support for his college years will be unqualified. What is in life? With the money will come responsibilities.