i mean, i don't even know who came before or after him, but me, someone who has never been in the USA knows most detalis about his personal life and family.
Just a clarifying question, since OP seems to be not a U.S. native. Do you not know any of the other "(in)famous" presidents from the scope of r/AskHistorians (e.g. Washington, Lincoln, Roosevelt, Nixon)? Or are you asking why JFK's personal life is more well known?