Plato did not suggest ancient Atlantis existed. He was very clear that he was illustrating a hypothetical "great society" to discuss his views on effective and beneficent government.

When he discussed it sinking it was a divine punishment from the gods of Olympus because they had strayed from a righteous path. All of it is meant to be a parable.

It’s damaging because it adds doubt to any kind of scientific consensus.

“They” don’t want you to know that vaccines are dangerous.

“They” are only pushing chemo for big pharma.

“They” don’t want to admit that this was where ancient civilizations had some global empire.

It’s the same kind of attitude of “fantastical claim you can believe if you just dismiss all the evidence that you don’t like”

And that is very damaging because it further erodes understanding of the scientific method.

Anyone else remember when Joe Rogan was a harmless comedian?

The belief in the existence of a super-race (or whatever term Hancock uses) is dubious. While the idea on its own may seem harmless, it opens the door for racist idealogies. Everything has to be taken in context, and crackpot archeologists have been making this argument for ages in order to justify later arguments for eugenics.

I know it may appear that Hancock questioning the established historians and "big archeology" is above suspicion, but it is done in an unambiguously dishonest way. He refuses to acknowledge sound logical arguments put forth by multiple well-respected sources and hand waves things away as common sense. Essentially, he is frustrating because his arguments muddy the waters of logical discussions and introduce doubt in a community that certainly does not get paid enough for this shit.