Not all. I have one headed to seminary. And the other will soon graduate a Jesuit institution with her (protestant) faith intact. It depends on how well grounded they are when they go off to college.....
My kids were warned by some misguided but well meaning Christians to NOT go to secular colleges because they would *lose their faith*.
And yet they did go to big name secular universities and came out, faith intact in spite of some of their professors efforts.
But they went in knowing who they were in Christ and what they believed.