SJS, I remember when that study came out. The 25% stat is just the tip of the iceberg. (It’s available for perusal on the Avichai foundation website, for those who want to read it.) Even kids with strong beliefs can’t help but be affected by an immoral atmosphere which pervades on colleges. the constant battles wear you down. It’s also hard to generalize and say “all 25% of Orthodox students who went off were overly susceptible”. The plural of “anecdote” isn’t “data”.
20% of a job skill is learned in college. the other 80% comes from on-the-job training. (I read this in my college textbooks). Does the slight gain in pre-job training warrant playing Russian Roulette with one’s neshoma? Furthermore, is 25% lose their Orthodox affiliation entirely, it’s hard to imagine that such a high casualty count doesn’t affect the rest. If a nasty battle on a battlefield causes 25% of soldiers to return in body bags, you can bet that many other are wounded.
(This is ignoring the debate if college itself is permissible. Joseph implies that college for parnassah purposes is muttar according to most poskim but never spells it out. I am hereby doing so for him. As always, Ask your LOR)