I'm not the person you're replying to, but I am someone who has watched the spread of covid denialism, anti-vaccination views and the the news media (which features stories such as: https://www.bbc.com/news/world-us-canada-52407177 ).

It doesn't seem to me to be much of a stretch to state that people who espouse the flat earth theory also espouse other conspiracy-theory views as well. What exactly, if anything, makes that difficult to believe for you?