I think what went over your head Donald Trump's detractors have called him a sociopath, psychopath, and narcissist. They are also known as Democrats.
You are making comparisons that mean absolutely nothing. Nothing can change the fact he bounced back from almost dying to continue fighting what he believes in.
As far as Reagan goes he turned to his boxes of cards with one liner jokes and hid what he was thinking behind them
JFK was assassinated 60 years ago I have no idea who said what at the time and neither do you.
They are professors of psychology at Ivy League colleges (ie universities) asked for their thoughts by media outlets in much the same way John Curtice is asked about politics and politicians in this country. They analysed his language and actions in various situations. One explained how he was invited to play a round of golf with him and Trump wanted to pay him to lose in order to claim victory. He sets up golf 'competitions' in which he is the only player so that he can claim victory and lift a big trophy.
And, according to those who accompany him, he cheats. If he doesn't like the lie of the ball he moves it, if he hits a bad shot he doesn't count it.
So that has nothing to do with politics but it shows what he is like as a person.
HIs presidency was not particularly successful:
Statistical indicators of President Trump's four years in office.
www.factcheck.org
He didn't bounce back from almost dying. He got a cut to his ear. To say he bounced back from almost dying is like saying I bounced back from almost falling from a second-floor window as a child. It's insulting to people who spend months in hospital with injuries or illnesses that see them close to death which would almost certainly have happened but for the intervention of medical staff.
The people who 'take one' are the ones who throw themselves in the way of bullets in order to protect someone else.
Reagan was seriously wounded and ultimately could maybe crack one liners about it but he never ever said he 'took one' for democracy or for the country. One of his staff died as a result of the attempt.
The JFK situation has been covered and replayed countless times down the years. No one ever said he died for democracy or for his country. Despite arguably being lucky to win the presidency they all decried the act that he had been taken so young and actually growing in popularity across the country.
Trump picks up things he hears on TV and applies them to himself because the soundbites that appeal to his mentality also appeal to the people who like him.