I never said anything about going to college. I actually don’t think people should attend secular colleges.
I think it possible you may be misrepresenting “bitul Torah”. Bitul Torah is not engaging in something that isn’t Torah, bitul Torah is engaging in wasting time. Why, then, is it called “bitul Torah”? Because engaging in other activities are necessary and beneficial and fulfilling, and you are being mevatel torah when you are doing nothing of value, because it is then you should be learning.