Every single instance of genocide in the last 150 years or so started as just some folks expressing a relatively fringe ideology, with plenty of others debating against it vigorously. For whatever reason, that ideology caught on, and then the mass murders start.
People, as a general group, don't evaluate their beliefs in a rational manner. They are biased in favor of the first things they heard; and whatever is most palatable given their emotions and things they already believe.
It's how you can get into a situation where massive numbers of people believe some combination of the ideas earth is 6000 years old and also flat and also that 5G causes covid and also covid was a hoax and face masks are just a mkultra trauma psyop run by the pedophile satanic illuminati cabal run by Hillary Clinton and George Soros.
If people can hold all that in their heads, and not believe any evidence to the contrary; then the idea of suppressing the notions that Black folks/Jewish folks/Muslims/migrants/whatever are the root of society's problems and we should do violence to them starts to make a lot of sense.
I also think that the idea that markets, particularly abstract ones, such as the "free market of ideas" are capable of producing long-term positive outcomes for most participants is, at best, without evidence and at worst pure fallacious thinking.