I was wondering about this myself since I saw Milo Rossi's intense takedown of Shayne Truth Vibes, another anti-vaxxer and overall conspiracy theorist https://youtu.be/-gxg7l_Hxa0?feature=shared. He's explained it as predatory behaviour that feeds fears to promote whatever it is they are peddling as the one and only solution to these fears.
Isn’t it a coincidence that the loudest voices against vaccines also earned their wealth peddling supplements on their shows?
https://roganrecs.com/supplements (Joe Rogan founded Onnit)
https://thealexjonesstore.com/collections/supplements