There's always been a few medical doctors getting in on the antivax grift, even way before covid was a thing. They're basically guaranteed to be cited by every antimask chud in existence, get invited to conferences and rallies, sell their homemade "vaccines" to their followers etc., so as long as there's not too many of them around, it's highly profitable.

Edit: ofc it can be tricky to stay a licensed MD when you're handing out bucketsful of obviously faked "i can't wear a mask for medical reasons" certificates.