On December 15, 1960, a would-be JFK assassin was arrested. Richard Paul Pavlick, a retired postal worker, had long been known as a tinfoil hat wearing kook who showed up at political rallies, ranting about how Catholics were planning to overthrow the American system and replace it with leaders loyal to the Holy See.
RPP decided to try to ram the President’s car with a car filled with explosives. However, when he saw that the President was accompanied by his family, he got cold feet and decided to postpone the assassination.
The only problem was that, in the fashion of a true tinfoilist, he spammed various papers with crazy letters even while on the road, stalking JFK. Someone who received these letters found it curious that the post stamps matched the President’s itinerary and alerted the police (this person should probably himself had considered a career in law enforcment).
Apparently, it was possible for a lone person (in more than one way) to plan and almost execute the assassination of JFK. Which is probably why RPP hardly ever figures in any JFK related conspiracy theories.