I've been fascinated with liars since way back, being related to a few of what I call "Storyteller liars," basically those who don't lie just for excuses or gain, but rather telling elongated convoluted tales that are supposed to impress with fantastic details, be it about ghosts, UFOs, basic crimes, accomplishments.... George Santos is a good example.
When I was a teen I had even asked a rather close relative, "Wait, do you actually believe that, you know, in a way, believe your lie?" because I wondered if any part of her really crossed that line into delusional fantasy. And I'm not talking about Schizophrenics who really can't tell at times and the lines blur in a slurry of psychosis, I guess these would be Borderline Personality types.
I still don't get it, too ridiculous to believe but does something in them allows them to push themselves to be deluded because they need it so badly?