One of my choir directors is a flat earther. Thankfully she never talks about it during rehearsals. I recall when she was first considering it, we had a long DM exchange on Facebook. I thought I was giving her good, factual arguments, but if people sincerely want to believe something, they will believe it. I mean look at our presidential race here in the US. How is this even close? But it is natural for people to want to belong to something larger than themselves, so they will adjust their beliefs accordingly to gain entry.