That's exactly the point. There are people that play games, or read books, and self-insert into the story. All it takes is a surprisingly little amount of empathy and imagination. I would read books or see movies growing up and identify with the main character, or put a lot of myself in my D&D characters, or pretend that I was the one smashing the bad guys in the video game. That's how a lot of people play video games, and why a lot of games -especially adult games- allow you to do stuff like pick your own name, or customize your character, or keep the MC's appearance hidden so that people can more easily imagine it's them. Just because you seem incapable of making that perceptual shift doesn't mean others aren't.