A friend of mine has a term she uses -- "Mary-Jane" or "Mary-Sue"-- to refer to characters people play that are basically just like themselves, but with absolutely no flaws. They're prettier, smarter, more athletic, and never have to worry about real-world issues. My friend always uses the term in a derogatory way, but I can see how a bit of escapism could be healthy for some poeple.
I DM most of the time, so I like to think that playing a lot of different people requires me to, at least slightly, think about people's personalities and behaviors. I discovered there was this one NPC that everyone really seemed to like, because she was generally helpful and cheerful. So that's how I like to be. I'm a bit too absorbed in some of my own projects sometimes, but I try to rationalize that I'm working so I'll get to a comfortable enough point in life that I can devote more time to helping my friends.
I had a friend whose character had all the same personality flaws as her, and I had to be really careful DMing her. I was rather, how shall I say, shocked, when, well, . . . um, she practically had her character do the D&D version of committing suicide. She had been feeling useless for a while, rolling badly, her ideas not working out as she'd intended. So when it came down to the climax, while the rest of the party was fighting to stop the ineffable evil, when the monster attacked her, and her only way to run was to jump off a bridge to her death, that's what she did.
It was really difficult to deal with. She was a bit of a character actor, so I wasn't sure if it was her playing her character as feeling depressed and useless, or if she was actually depressed herself. The rest of the players were having a good time, and were really into the situation, which was a little desperate, but not hopeless. The rest of the group, thankfully I guess, assumed she was doing it in character, and so they leapt to grab her. One of them dangled to hold onto her while another PC held the monster at bay, and a third fired a rope with an arrow tied to it so she could grab on.
Afterward, I talked with her, and she said she was surprised that her friends had saved her. I laughed and assumed at the time that she meant she didn't think the characters would have risked themselves. But the more I thought about it, the more I became confident that she actually thought her friends in real life didn't care about her.
Man, high school really screws with some people.