I recall reading in U.S. History class that both McKinley and Garfield would have likely survived with modern day medical care, but Lincoln and Kennedy would have still died from their severe head wounds.
Leon Czolgoszan didn’t live to see Halloween. Justice was swift in those days. He was tried, convicted, and executed in about six weeks.
Reagan came awful close to dying when he was shot. Before Obama, I’m wanting to say that presidents only had 10 years of Secret Service protection after leaving office. Obama changed that to lifetime.
If I was as disrespectful of the nation and Constitution as he was, and continued to undermine things after leaving office, I would probably want lifetime protection, too.