>If you say the sky is blue I'm going to say it's green because I'm so smart.

Flat-earthers are definitely wrong about the shape of the earth, but even they admit the sky is blue, assuming they aren't afflicted with some unfortunate variety of colorblindness.

In my observations of flat-earthers, they're people who reject the consensus surrounding a particular fact because they haven't observed that fact for themselves, which doesn't make them bad people or even crazy. I do rather enjoy their attempts to measure basic scientific facts about the earth, such as when a group of flat-earthers used lasers and the ocean to measure if the earth indeed has curvature. When the evidence incontrovertibly showed the earth indeed has sufficient curvature to match the scientific consensus, many participants were quite shocked. As long as they adjusted to the consensus, or even hypothesized another theory they felt worth testing, they're not crazy, just skeptical of authority.