"Psychological projection is a defence mechanism in which the human ego defends itself against unconscious impulses or qualities (both positive and negative) by denying their existence in themselves while attributing them to others.[1] For example, a bully may project their own feelings of vulnerability onto the target. It incorporates blame shifting and can manifest as shame dumping.[2"
https://en.wikipedia.org/wiki/Psychological_projection
"Ad hominem (Latin for "to the person"), short for argumentum ad hominem, is a term is applied to several different types of arguments, most of which are fallacious. Typically it refers to a fallacious argumentative strategy whereby genuine discussion of the topic at hand is avoided by instead attacking the character, motive, or other attribute of the person making the argument, or persons associated with the argument, rather than attacking the substance of the argument itself."
https://en.wikipedia.org/wiki/Ad_hominem
The Sad Truths of Internet Trolls
Serious trolls are immune to criticism and logical arguments. True trolls cannot be reasoned with, regardless of how sound your logical argument is.
Serious trolls do not feel remorse like you and me. They have sociopathic tendencies, and accordingly, they delight in other people having hurt feelings.
Trolls, in general, consider themselves separate from the social order.
Trolls do not abide by etiquette or the rules of common courtesy.
Trolls consider themselves above social responsibility.
Trolls gain energy by you insulting them.
Trolls gain energy when you get angry.
The only way to deal with an online troll is to ignore him or take away his ability to post online.
https://www.lifewire.com/what-is-an-internet-troll-2483704