It's the confluence of several factor, but essentially, suspicion of the Medical Industrial Complex has been building since the mid 80s. Medical care is so expensive and the MIC so squirrely that it always had people desperately looking for ways around it, which opens the door to con artists. In the mid 90s, discredited now but not at this point in the story British doctor Andrew Wakefield was invested in (and I think part inventor of?) some new vax that targeted one of the components of MMR. In order to market it, he published a paper suggesting (quite softly iirc) that the MMR had some flaws, and advocating for parental choice to vax for each separately.

This is hogwash. The MMR has been safe and in use for something like 100 years (possibly more?). Wakefield was disgraced for this, and when the paper was cherry picked (even after the Lancet retracted it) and misquoted by the then still quite powerful but not yet in their final form anti-vaxxer movement, the disgraced Wakefield had to pivot to a new grift; speaking to Anti vaxxer gatherings, and lending them credibility to those who did not know the story (for which he did have medical license revoked).

So it follows with all of society's issues in the 2020s; Instead of fixing a severe systemic issues, like say, our broken medical system which bankrupts people or kills them because they cant afford life saving medicine, which might involve curtailing the power of capitalists, blame instead pivots to the products instead, which people can understand. They understand their child is dying and they cant afford it, while maybe not questioning why. This opens the door to con men, which starts a cycle, as conmen want to open the door further. The conmen become the power, and then cheating just becomes business, and an army of marks becomes numerous enough that RFK becomes secretary of health, and your mom dies in a hospital hooked up to a ventilator refusing treatment because a conman said a fucking horse dewormer that he owned shares in would protect her.