The ones that made it to Florida were the former ownership class that had the choice of staying to face trial for their crimes against the Cuban people, or get on the boat. Occasionally a "politically persecuted" person or group would "escape" in later years. Usually these people either helped the CIA with their destabilization attempts or were just ordinary criminals that fled prosecution like many Americans go to Russia to do. The US was more than happy to accept both groups without any vetting as that helped their narrative that Castro was a tyrant making up charges.

Floridian Cubans, Gusanos, hate communism for the same reason anyone in the parasite class hates communism; they're mad the playing field was leveled and they had to answer for their crimes against humanity.