There was a second Fyre festival documentary released recently by Hulu which is really worth the watch.
Jerry Media was heavily involved with the production of the Netflix one, and it downplays their role in the fiasco.
I watched both and they are thoroughly entertaining whilst presenting different sides to the same coin.
My read on McFarland was that he always wanted to be one of the 'cool kids' and this was his way of doing it. Right up until Fyre blew up, I think he genuinely believed he was going to pull it off and this wasn't a Lyle Lanley situation.
Even his idiotic follow up which landed him in prison was I think his attempt to redeem himself.
I think there was an element of mild sociopathy to him, in his constant lies and robbing Peter to pay Paul, but I really think he thought he was going to pull it off and be the next Zuckerberg.