They get recruited. It’s like any other cult. They find vulnerable and minority groups, and claim they support them. A good example is the trans community of the US. A large number of them (on Lemmy) are very very brainwashed by the Chinese tanks, yet they would have the same or fewer rights over there. Call them on that and wait for the explosion.
That and the actual numbers of tankies are far less because they employ bots and alt accounts to inflate their numbers.
Example, countless times have I made a comment that triggered a tankie. Then, out of the blue a dozen other accounts will swoop in to back up the tankie. This is propaganda, manipulation, gaslighting, and whatever other words you like. It’s likely this is all controlled by one person, and not a dozen individuals who were not instructed.