To consider your online reputation as worth defending only encourages others to take perverse pleasure in denigrating it.
This is not the fault of social media; it does not divide us or make us worse.
The capitalist system we are in plays out as subversive competition on social media. Enjoyment through dissidence is encouraged, where trolling builds a reputation by destruction, which converts the troll into a king, who then must be subverted or torn down in turn.
In short, to consider the online self as an extension of your reputation (worth defending) is the trap into which we must not fall.