Can't understand why people prefer to go to UCs, anyone tells me?

I have read the post says that this year OOS students will not get any aid, so we’re all going to pay full tuition. However, UCs’ lower divison’s lectures are all large, most popular classes are almost all around 300-400 students, and even upper division classes of popular major still have more than 100 or 200 students. You pay tuition as a private school but receive a public school education, even worse than other great public schools with smaller average class sizes. Why do they even want to go to UCs? So those are people who don’t care so much about education quality and costs? Or I overestimate the negative effect of large classes?

The weather is good (and California has a few but not many top private universities).

Also, for CA residents, it is way cheaper than any other school. In this age of high college costs, that matters a lot