I'd imagine there are those of you who have had similar experiences, but I don't think RY's personality is unique by any stretch among runners. I knew just such a runner.
Several years ago, I met a runner whom we'll call Jason, following a 10K that a ran, in which he also participated (finishing behind me). He was friendly enough and talked about his training and his aspirations in the marathon. At the time I had similar aspirations and so we went for a few runs together.
I quickly discovered not all was right. That outgoing, friendly personality revealed a narcissism that impressive in its scope. All conversations inevitably returned to him and how he was going to quality for the OT marathon later that year, how he was going to make the World's team.
But his actual ability didn't seem to gel with his aspirations. He struggled to keep up on a six mile run, despite claiming to be running two a days, and logging elite level weekly mileage. He had a poor running form, almost knocking knees and pronating to the point that I wondered if he'd even been fitted for a proper set of trainers.
I eventually stopped running with him, but he would occasionally turn up at group runs with the local sub-elite outfit. By now, his character took on a new angle, as his bluster turned to outright exagerration and falsehood. He claimed Powerbar was sponsoring him, when in fact he was just getting free samples that Powerbar gives to anyone who claims to be a coach or trainer. He claimed outrageous times that he couldn't back up, such as having broken 15 minutes for 5K on a track.
At area races, he consistently underperformed, running 19 minute 5Ks, and always he had an excuse...he took a wrong turn, he tripped. His favorite excuse was that he was using the race as a training/tempo run. Over the course of a summer he managed to alienate the entire running community by claiming his superiority in racing. Several challenged him to races, offering to comp his entry fee. He never accepted, but continued to claim he was the best, without any proof.
Eventually he lost every shred of credibility he had. He was a decent runner, but could find no one to run with because everyone was so thoroughly tired of him.
I think RY is the same type of personality. He's a narcissist in search of a source to validate that narcissism. He has made increasingly outrageous claims that don't seem to be backed up by anything, and now finally the wall he has built up around himself is starting to come down as more people call him on it and challenge him to prove his mettle.
I feel very sorry for him.