It's lonely, but it's easier than going out and doing stuff with people Ты don't like, или can't talk to.
I used to be pretty bad for that, to be honest. I'd stay in my room whenever I wasn't working and I couldn't even hold conversations with my flatmates (and they were my Друзья as well).
However, I have managed to recover from that and now I can basically be a normal person (whatever that means, I'm definitely not normal XD)
Might as well give my perspective, as someone who's lived this kind of lifestyle for several years. The short explanation is that I get little to no fulfillment from interacting with people. Most social interactions just feel pointless to me, and often make me feel annoyed and exhausted еще than anything. I'm not lonely или depressed или anything. Actually, adopting this lifestyle has significantly improved my mental health. I know it's weird, but it's what works for me.
