Flat-Earthers can be categorized into the following groups:

1. Real Flat-Earthers
1.1 "Muh Bible!"
1.2 Parroting what other Flat-Earthers tell them, don't do experiments.
1.3 Doing experiments but not knowing what they are doing and/or actively trying to force a preconceived outcome.

The Flat-Earther Anthony Riley posted a video of himself trying to measure the density of a liquid with an instrument that measures conductivity and THEN immediately dismissed his own measurement as "just a number".

The Flat-Earther Bob Knodel accidently proved Earth's rotation with a laser-gyro and then dismissed his own measurement by claiming that his laser-gyro had picked up the rotation of the "aether" in the sky.

The Flat Earth Society has invented their own theories of electromagnetism and gravity, except that they refuse to test them via experiments, their theories are full of holes and contradictions, and if you ask questions you get banned from their forum.



2. Fake Flat-Earthers

The Flat-Earther Bob Knodel, who denies the existence of space and space-travel, made a cooperation with a conspiracy-outlet that invented the conspiracy-theory that NASA cannibalizes children on a secret base on Mars.

A certain Flat-Earther (forgot his name) was in a livestream, discussing the visibility of a certain light-house with a normal person. The Flat-Earther Nathan Oakley was caught (via screenshot) warning his fellow Flat-Earther that the example was (quote) "perfect proof for a Globe-Earth" and telling his fellow to end the discussion and change topics.

They keep going because they are making a living from the donations of real Flat-Earthers.