Some are bots, but others are real people that were influenced by the bots . The Asch Conformity Experiments suggest that up to 35% of the population will adopt what they perceive to be the majority opinion.
In psychology, the Asch conformity experiments were a series of studies testing the Asch paradigm, directed by Solomon Asch, studying if and how individuals yielded to or defied a majority group and the effect of such influences on beliefs and opinions.
Groups of eight male college students participated in a simple "perceptual" task. In reality, all but one of the participants were actors.On the first two trials, both the subject and the actors gave the obvious, correct answer. On the third trial, the actors would all give the same wrong answer.
-Wikepedia