>The more I read about it, I’m convinced “loneliness” is an upper middle class problem.

Yeah, exactly. You trade a social life for financial stability accompanied by loneliness. I've had one or the other, but not yet been able to find a balance. It's, very, very hard to do except for the few among us who have a highly desired technical skills (check) and excellent marketing skills (uh, nope). Those folks can run successful freelance/consulting businesses, work reasonable hours, and still make good money.