Here’s a video on this topic.
https://www.youtube.com/watch?v=aK46MUXlM50
My friend who I studied abroad with goes there now, she said if I went i’d be the most social person on campus and that it’s pretty dead. I’ve visited the campus a couple times, but I think any school you can have a good social experience if you put in the effort. However, I think at UCSD you might have to put in a lot of effort compared to other campuses. It’s not high on my list because its in SD, no sport teams, and also the lack of a decent social scene. I don’t want to get rejected from there, but if I got in i’d probably end up at a CSU if I dont get into the UCs I want to get into.