Some of the best games out there are single player games. I play games with my friends so often that I like to boot up a game to play by myself now and again. Every single time I log into Xbox Live I'm assailed with invites for Halo, Mass Effect, or Borderlands, and sometimes I just want to be left alone to play Hitman or something. I like an offline experience. I can take it at my pace and enjoy my game the way I want to without the judgement or time-constraints of another individual.
An awkward example of this is Star Wars: The Old Republic. It's an MMO, so there are lots of people running around, especially now that it's free to play. However, you can solo the entire storyline of your class if you so choose, and I damn well do choose to at times. I have characters that I play with friends and then characters that are just for me. I don't even go looking for random groups to do certain quests. I enjoy playing by myself, but I also like the feeling that I am a part of a larger world, and the people are there in case I get a hair up my ass and decide to invite one of them to briefly join me for a quest that requires more participants.
I'm glad this came up, actually. Just the other day I was playing SW:TOR and I had a guy bugging the shit out of me for soloing and not playing with other people, who then spent the next half-hour explaining to me that I needed to get into the end game or I was just wasting my time, despite that fact that I was having fun as it is. I fucking hate it when people try to tell me how to have fun in a game; it's their way and I respect that to the extent that being pleasant requires, but that doesn't mean that it should be everyone's way. It's something that's irritating particularly in video games. You play Call of Duty, but you don't... play the multiplayer?! You're crazy! The multiplayer is the best part! Play it! Play with other people! You don't know what you're missing out on!!
I do, as it happens, know what I'm missing out on. I have my co-op games that I won't play without my friends and I have games that I enjoy simply to be by myself. It's nice to get away from it all. People read books for the same reason and you don't see other people running up to them and shouting "what are you doing?! Stop reading by yourself and come read with us!!"
I think this is pretty much the longest 'I agree, Jim' post I've ever made.