I'll buck the trend. I donate to my alma mater and I paid to go there.
No one who goes to school in the US actually pays for their whole education, even if they pay sticker price for tuition and books every semester. Public universities are funded by state and (some) federal taxes and private school tuitions are subsidized by endowments. Even when tuitions are ~20k-30k per year, the actual cost of running a university hovers between around 40k per student for public and much higher for private. I believe I paid 21k for my last year of school and I think I saw that the cost was somewhere around 60k per student.
The endowments pay for quite a lot at both public and private institutions. I'm much more comfortable giving money to my school since they don't spend millions each year on minor league (ahem, I mean
student athletes) football and basketball programs.
(One interesting tidbit about my school's endowment is that it still contains the stock that George Washington gave in the 1790's - $50,000 of James River Company stock - quite a lot in those days. Old George helped pay for my education.
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