Yes, I’m sure there is some self-selection, but as I’ve described here (in the last few paragraphs), there’s also anti-conservative bias by admissions officers going on.
As far as self-selection, it’s interesting for me to wonder how that would apply to me today. Yale was my first choice when I was choosing colleges because I knew I wanted to be an English major, and Yale had the best English department in the country at that point. Today, however, I don’t know if I’d even apply there. It’s become a total circus, and I’ve even refused on principle to go to my 20-year reunion, as I’ve described here. The sad thing is that this self-selection is going to keep becoming more and more of a factor as time goes and as we hear about more and more absurd goings-on at these universities, and that’ll result in even fewer conservative students choosing to apply, which will make the atmosphere even more extreme. Hard to reverse that cycle once it gets going.