90k is by no means optimistic; new grads at any of the BigCos start at 100k base not including bonuses, stock grants/RSUs, or relocation. If you're highly marketable due to internships, personal projects, etc. and have multiple offers, that can be easily bumped up by a significant margin. Additionally, if you're capable of making it into one of those top schools and then, again, into the CS department, you're more than likely eligible for numerous scholarships and other merit-based financial aid. To end up with 250k in tuition would require you to come from an extremely wealthy family who refuses to pay any of the cost of your education, and likely spending more than four years at university as well.

Internship pay (assuming one position as a rising Freshman, Sophomore, and Junior) will add up to 60-70k, and contracting could be another 5-10k for only a few hours of work every few months. The benefits are, as you yourself mentioned, being able to indulge your passions and dive into esoteric areas without the pressures of the real world. Had I dropped out of university I never would've been able to pursue my interest in quantitative literature, my ex-roommate would never have taken the dive into distributed systems, both decisions which have had a net return over not going, even accounting for lost salary.