Would all the people who treated Djokovic so poorly, want take the treatment he paid to have developed?
Who would care that? When the subject is self-interest, they forget their past, ideas, nationality, religion and so on. A pandemic that can't be finished despite several vaccines in almost two years. Therefore one could easily suspect about vaccine and not want to get it.
There are so many illogical conditions around vaccines and passports and the like - yet most people don't seem to think. This is normal behavior akin to those people who click links in discord scams saying they wone 5 Bitcoin.