Not to mention the fact that for hundreds of years, some of the most highly educated and trained observers in society, being sea captains, naval officers, and navigators, reported seeing "Mermaids" in the ocean, being half women and half fish. They even sketched detailed pictures of them on their maps and in their sea journals. They noted them in their reports to the Admiralty.
So, I am always stunned that people are willing to believe in some mythical creature, merely because other people claim they saw one, regardless of whether those people are just regular folks, scientists or law enforcement.
Oh, and lets not forget that about 4 percent of society are sociopaths (compulsive liars), and probably another 10 percent are just braggarts and exaggerators, who lie to get attention.
The OP said that he could understand why people don't believe in Bigfoot, because of the things they have seen on Youtube. No, the vast majority of people don't get their scientific information from watching Youtube. The reason that people don't believe in Bigfoot is that there is absolutely no credible physical evidence of any nature to prove or demonstrate that it exists.
During the first quarter of the 20th Century, particularly in England, there was an extreme interest in the occult and in the paranormal. Educated people routinely reported seeing fairies and pixies. Do you believe in those too, just because people said they saw them?
Go take a visit to Ireland. Even today, many older folks swear to you that they have seen "the little people". They will tell you about it in great detail.
Mannyrock