Can someone explain something to me?

It's one of the few times the fat guy misread "the base" by revealing his own true fear of the virus. The idea that they will bend to his will is really an optical illusion. They bend, but that is only the case when his will bends to their conspiracy orientation.

So, when he claimed he was draining the swamp, that played into the conspiracy that there is a swamp. It didn't matter to them he actually created a swamp. When he claimed the "deep state" was doing behind the scenes obscene acts (like eating babies), they signed up to it without any proof despite his association with Jeffrey Epstein, his interest in grabbing women by the pussy, etc. He gave "the base" what they wanted to hear and it looked like they were following him.

Now, "the base" was largely already on the anti-vaxx train before he took centre-stage. For example, they believed in "measles parties" for their kids, etc. So, when he got behind the COVID vaccine, for a virus that he initially called a hoax, they wouldn't go along. In fact, there is a formidable segment of "the base" that doesn't believe he really took the vaccine even though he has confirmed he has.

His power isn't so much he can direct "the base." It is more that he has a knack for telling "the base" what it wants to hear and then standing in front to make it look like he is leading them. If you look closely, they are actually dragging him.