Flat earth theory
There's a lot of valid arguments for flat earth- or at least for issues with the round earth theory that we know.
I hate how round earth era try to belittle the intelligence of flat earth earthers but have clearly never actually thought about it at any deeper level than "that's stupid". The typical proofs that are give in response are a joke.
That said, after studying, I have found massive holes in both theories.
The flat earth theory doesn't work for the sunset - the sun dropping under the horizon doesn't work with the "perspective" theory given by flat earthers- it's just wrong - demonstratively wrong. People who put a quarter on a table to show how the sun goes down are not thinking clearly- the sun is not at sea level, but supposedly 3,000 miles high- try the experiment again with the coin high above the earth and you'll find it fails miserably- not to mention that we should see the sun curve away and to the right as it's trajectory circles the earth in the current flat theory.
another issue is the lunar eclipse- the earth must be causing the eclipse- which means that the sun must be on the "other side" of the earth- and the earth must be round at least. Problem is that if the sun was ever on the other side of the earth, all nations would be in complete darkness (night) at the same time.
All this said- and I still don't believe we've been to the moon- or any of the photos of the earth are real. To me this is one of their biggest reasons for my skepticism... along with the gyroscope in an airplane, watching the horizon with a telescope- Chicago skyline, etc.. to me it is clear that the earth is reflected at a distance by the atmosphere- which creates the visual illusion of the bottom of anything (ship, buildings) disappearing. I'd like to see a higher powered optical zoom to show what happens because it's clear even the basic ones bring things back into view.