Unimportance

Why do we find our own self completely unimportant? yet others like to disagree with that opinion... And i know they're not just disagreeing for any reason other than that they truly do disagree. i have disagreed with someone for saying they don't matter. Do we live for others? No, we live for ourselves. So i guess it doesn't matter if they disagree.. however, if i was on the other side i know I'd completely bitch myself out for saying this. I certainly would do everything in my power to prevent my friends for feeling this way, but not for myself. I'm in the -suicidal, i hate myself and my life- kinda mood...