"btw you can say anything you like to me, anything at all, you'll never hurt me or even upset me.. I do not care because I don't care about you .. I don't know you .. I would not know you if we passed each other in the store"
It is funny when you think about it, it's possible that some people on this website have passed by each other in real life and didn't know it
"so How could some nobody that has no bearing on my life use a word to hurt me?"
Not you or me in particular, but in general people can say things that are hurtful. If you're married to somebody, and they suddenly tell you they don't love you anymore, I bet that would be pretty hurtful. If a parent told their child they didn't love them, that would be very hurtful. Obviously it's different if some random person on the Internet says something mean, because like you said, you don't know them so their words don't really matter.
"See what I mean.. the same goes for me and you - how can i hurt you when I mean nothing to you?"
Not you specifically, but it is possible for someone to say something very mean, and it can hurt somebody's feelings, even if they don't know the person or even really care about them. Getting to the point where you don't let other people's words bother you takes a lot of work for some people. For others it comes easily.
"People need to stop caring what other people think"
I agree. But it's often easier said than done
