He's not but I understand why he could be considered overrated. And to be honest, he's such a shytty human being that talking about Ric ain't even fun anymore
Flair was considered the de-facto GOAT wrestler by hardcore fans for practically 2+ decades and even for more casuals or WWF/E centric fans he was always in the discussions for best ever. That's a status that's practically impossible live up to when you don't have nostalgia going for you. What I mean by this is that Flair's prime was so long ago that people that would go to war to defend and stan for him are no longer online (shyt, a lot of them probably never were) to drive those discussions. You then add the fact that Flair's prime wasn't lived/seen weekly by the vast majority of the current wrestling fanbase (and they probably base what they know of Flair by his promos, and 90's-00s work) and it's pretty easy to poke holes to a wrestler like Flair, specially when the case against him isn't that he was wasn't good, it's that he was "the best". So by that metric it ain't that hard to make an "overrated" argument.
To me though, I've seen dude be ridiculously entertaning in so many different time frames and settings and against such a mindblowing number of different wrestlers that I have no issue with him being a GOAT tier performer