The wild increases in tuition are for the nameplate price, not the actual price paid by median students net of grants. See pg. 12 here:

https://research.collegeboard.org/media/pdf/Trends-College-P...

Published tuition has gone up, but grant aid has matched it, making the net cost at 4-year public institutions to be flat, or even down slightly over the 10 year period. The same applies at private 4-year institutions, large increase in nameplate price, matched by large increase in grant aid, actual net tuition flat.

Expenditure data also show that they are not spending significantly more. See the chart at the end of this page, which gives expenditures in real, per-student dollars. They are up, a little less than 20% over 10 years, but half of that is increases in hospital costs of their associated health care systems, which have nothing to do with tuition. The rest is a mix of various activities of universities, much of which are not tuition-funded.

https://nces.ed.gov/programs/digest/d23/tables/dt23_334.10.a...