I mean, how many people in America do you suppose there are that would, given the chance, take Trump's orange head off?

Someone in England wanted to take the Queen's head off with a crossbow. Someone wanted to kidnap, rape, torture and ultimately kill a breakfast show host. Someone sent a bomb to Bjork and then filmed himself committing suicide.

It's extremely easy to believe someone would want to do this. It's harder to believe someone can do this without being spotted in good time, but it only takes one out of a hundred to slip through the net for it to be a bit more credible. This could be that one in a hundred, at least that seems the most likely explanation at the moment, given the information.