Well, while I did meeting a lot of tech people that had small social circles/seemed lonely, most of the people I know have small group of friends and are very happy with it, and I know even of some genuinly happy social butterflies that have large group around them.

Personally, it is hard. I.e. I met one of my closest friends when we started internship together, but it took us month before we went out together beyond work-lunch/coffee-break.

And even after few years it felt kinda awkward when I talked to him about my marital problems, and he was the one that called me on it. And I was glad he did, because I didn't really have people to talk about that ...