I could have sworn I responded to this thread already.
I LOVE DOING THINGS ALONE! Movies are more fun alone (unless it's scary) because I don't feel pressure to laugh when the person next to me laughs.
It's very much a fun "me time" thing for me. My first year of grad school, I learned the value of taking my books and going to a casual restaurant to study. Most people do this at coffee shops but restaurants were fine with me doing this, too. I would ask for a small table out of the way and just study while ordering drinks and/or food. I made friends with the servers who got to know me and my regular seat. I agree, I wouldn't go without something to read but I definitely don't need another person to study, pleasure read, or people watch.
I also do beach days and road trips alone. I have been to concerts alone. Honestly, I don't like the pressure of having to find someone willing to go with me, who doesn't mind the cost of the thing I'm going to do (or try to include things in the trip that are out of my budget), etc. I can't stand having to alter my plans because the other person backs out last minute. I don't mind adjusting for things that were meant for two or more people from the beginning (an outing with friends or an SO) but I'm particular about my casual "me time" activities. I'd rather them be just so.