I think you give flat earthers to much credit. It would better if this is true, but sadly, people honestly believe in a flat earth. I will show you the video of the flat earth conference.
"We're not crazy! *Cheer* "
I would say, flat earthers are either in denial, have major learning disabilities, combination of the two, or prescription drugs. At this point, I really don't care. They can believe whatever they want, just like Heliocentric believers.
Earth's shape is fascinating, but maybe what's more important, is what benefit does knowing the earth's true shape? That's really key I think.
For me believing in a Concave Hollow Earth, I feel God is closer, is in control, and allows to me filter out things that are a waste of time. Such as space aliens, moon landings, space travel, unknown galaxies, and faulty science. It really explains reality to me, that can be proven, rather than some lab coat spouting off scientific formulas (That can't be proven right or wrong). It also allows me to laugh at NASA, which is fun.
I wish people in NASA and the scientific community could just admit, that they don't know things, and present their information as it is their best guess, but it is rarely presented that way, if ever. This leads to further laughter in my view point, but they have to sound convincing, since they are getting government funding.