There are a lot of reasons for the rise in the cost of college and the amount of debt (see this Forbes article for a very partial discussion of the reasons: https://www.forbes.com/sites/camilomaldonado/2018/07/24/price-of-college-increasing-almost-8-times-faster-than-wages/#1872f2f466c1).
As @cshell2 pointed out, the cost of state (public) universities has risen particularly quickly, in large part because of the desire to cut taxes, which requires cutting spending, which means that the average subsidy for in-state students has dropped dramatically (for examples, see both the University of Virginia and the University of Kentucky, who have published charts showing the decrease in subsidy vs the increase in tuition).
There are other factors: the pressure to get a 4 year degree continues to go up, private (including for-profit) colleges have gotten really good at marketing, etc. Comfort with debt is (imo) a factor as well: cruise CC and you will see many posts from students - and parents) arguing that $100K of debt for Amazing U is worth it. The “I want the best for me/my kid who has worked so hard to get into this college” drive is strong.
Finally, there is a difference between saying ‘talented students should be able to come to our university’ and making spending decisions for college students and their families. No college can “strap” their students with mountains of debt: by law a student can’t borrow more than ~$20K total- above that a parent or guardian has to sign.