We shouldn't doubt him if he says he is a millionaire and also his uncle is. A millionaire can still be doing bounty hunting as a hobby or used to engage in the forum.
Another point is that he didn't specify the kind of million, he could be a SatMillionaire which should be the recognised millionaire in the forum. He could also be a millionaire in their local currency which could be equivalent to 0.0004 dollars.
The OP could quite rightly be a millionaire in their local currency that prolly wouldn't mean much, and i might also agree with you that even despite the fact that the story looks flat out fake, there is a slim chance they aren't telling lies.
Having said that, what i definitely disagree on is that they could probably be into bounty hunting as a hobby, who loves dumping tweets on twitter or making multiple posts on FB, TG and other socia media handles, coupled with bounty reports right after it all. The forum is for Bitcoin, crypto and other whatnot discussions, thus bounty campaigns is no way to engage in the forum, interacting and contributing to quality discussions is the way to do it, and you can then earn through signature campaigns whilsts doing thus.