For most people the awareness of flat Earth comes from a nagging doubt they can't resolve, like a seed planted in their brain. It eventually leads to research in hopes they can put the doubt to rest so they won't be threatened by crazy thoughts of a flat Earth. (Those flat Earth people are just plain nuts!) However, you gradually start to accept the crazy theory in stages. First you're 10% convinced, then 25%, then 40% and so on. The day you reach 100%, you wonder why you didn't see it sooner, it's so obvious! But you keep it to yourself mostly to avoid pointless arguments. No one can be convinced by someone else. They'll have to find out themselves.