I do think he's a compulsive liar. That makes the most sense of not only this but the long series of implausible claims or outright "misdirections" he's made over the years, his obsession with debunking other people's false gambling claims, his absurdly high posting volume (*posting* is his life), and the fact that absolutely nobody can verify anything he says.
And let us not forget just how insane faking your death is.
JBJBs evidence can be explained in various ways. Most charitably that KJ was at one time (or however many updates he has) actually counting and got databased. So? Would that actually corroborate his career?
But it also is perfectly possible someone who reported to OSN simply mistakenly believed that person was KJ. Errors like that happen all the time. After all how would the reporter even know that counter was KJ?
