Who knows if JFK was even part of the fraud or even had knowledge of it. Joe Kennedy really wanted his son to become President and LBJ, well, he was a fucking corrupt piece of shit. Wouldn't be surprised if Joe worked Illinois (one of Daley's descendants says no, but I don't believe any of those fucks and said "fuck" may not be privy to that info) while LBJ took care of Texas.
Oh just strictly addressing the fraud and agree, no one is perfect and that isn't a bar for doing good things. No one is perfect. Had Nixon been elected, we probably would've nuked Cuba. Among other countries. Just speculating based on his extremely volatile temper. So we dodged a bullet there.