For several years we had free tuition paid for by the lottery. At first it was full tuition until they started running out of money and now it is a little over 1/3 and they have tougher requirements. It’s hard to find data but the graduation rate is 30 to 45%.
When my DIL was in college most of the students were young women who didn’t pay a cent, most of them flunked out.
I paid my way through graduate school. I’m debt-free.
I did that long before Bernie Sanders came up with the idea of “free college.”