In my experience, there are four types of people here:
1) Those who genuinely believe in a Flat Earth.
2) Those who don't, but pretend that they do.
3) Those who believe in a spherical earth.
4) Those who are undecided, suspicious or intrigued by the idea.
However, from a practical perspective, it doesn't really matter what someone's 'real' beliefs are. So for the purposes of a research paper, it's best to just take every post at face value.
FWIW - I am in category 3. I'm not particularly interested in FET from a scientific perspective, I'm more interested in the psychological aspect of fringe science and conspiracy theory. I've written quite a few pieces over the years on the subject(s), and the Flat Earth Society has provided (by far) the most material.