When I look at my chest why do I feel attracted to myself? I mean I know my body doesn't care who or what I have sex with, but why myself?
It isn't so much an attraction as your awareness that orgasm and ejaculation is possible. I assume that you are feeling erections happen when you see yourself with your shirt off. If I hazard a guess, this is what you typically do before you masturbate. Thus, seeing yourself partly undressed reminds your body that you could go further and relieve the sexual pressure.