Sean Parker sort of reminds of a couple of guys that lived in the neighborhood I grew up in. If you ever saw the documentary Cocaine Cowboys these are those guys. Guys with humble beginnings as pilots and fishermen (in the 80s before the war on drugs got the DEA AWACS and nightvision) that stumbled onto something that made them insanely rich. After hearing their stories about 80s Miami and reading stories about Parker I can totally draw the parallels between them.

Its quite possible that most of the other characters were fictional but the writer seems to have nailed him.