I agree whole heartedly with this comment. Until last year, my family and I lived in the undergrad dorms at UCLA (as a professor in residence). In the end the major thing I’d advise students to do is get involved. It might be research, but there are a million other things as well, and opportunities to explore these types of activities become a lot more rare after you leave college.

I wonder if over the long term there might be a way to replace that experience too, because I agree with the OP that it’s the most valuable part.