I'm very very sure there are plenty of these with serious issues in the head in this field/cult/sport/whatever one calls it.. I've met quite a few. Sometimes pathological lying is explainable by just that - pathology.
I've recently been encountering one fella I've known for a long time. Not friends, but good enough. He wasn't able to bench press 225 for reps properly. Now, two years later, being like 30yo he's repping 375 with a relative ease, in addition to being a walking ocean of water (I guess dballz or oxy). Well, even to me, a "safe" person to tell (even tho' it's "safe" to do whatever you want and admit it, where I live) he's blabbing something about being clean for at least few years, etc, etc...
This is not comprehendable for me personally. Just smile and keep quite ffs, if you don't want to admit, but don't think someone who has been in the field twice as long doesn't know what's up lol..
I'm prettu sure people take it to a whole another level in US, because all the media brainwashing about "being the best", "being the superhuman" and so on. Noone wants to admit that they need some chemical "help" to be these "superhumans". Lying filts.