Vaccination has been opposed since the early 1900s because at the point of treatment, it hurts, with no obvious benefit (at the point of treatment). Your kid is crying because they are in pain, and no sane person wants their kid in pain. Of course, vaccines are worth the pain.
Some of these activists pushing the narrative are sincere. These people are useful idiots.
Others, like Andrew Wakefeld, are in it for the money. He wanted to sell an alternative vaccine, and make money. Others are doing it for the clicks, just like any meme these days.