REDO: ...wtf, internet. just refresh on me, why don't you... rat bastard.
*sigh* ok. redo my paragraph. I'll paraphrase:
You're getting invested because you're arguing with people. Stop it. There are no people on the internet. You may meet nice people occasionally, but they are the exception to the rule. And the rule is that the internet is filled with assholes. To become not invested, you must become aloof. To become aloof, you must stop talking with people, and start talking with avatars, with voices, with disembodied thoughts. But do not talk with people.
If you want to stop the assholes from getting to you, you will, ironically, have to become a sarcastic bastard yourself, most likely. Again, exceptions to the rule, and I'm only one person, my own example is hardly the rule.
To grow a skin, be aloof. Look at everyone like they're tiny insignificant wretches and KNOW that you are better than them. When you know that, their words mean nothing to you.
Laughing at their stupidity also helps. Because assholes are also naturally stupid.
Naturally.