This possibly counts for some of it, where you are just the collateral damage of somebody trying to disguise their bot as a real user. It feels unlikely to be the majority of bots though, but I could be wrong.

I'm not sure how many of these there are, but they're very significant.

These are bot networks run by big firms just building reputation overtime, to be switched on during some huge - usually political - campaign.

Suddenly, in some point in the future, all these "legitimate" looking "people" start inflating discourse against some political figure in some country and completely flip the democratic game.

It happened way too many times in the past decade.