Well we all know that's complete and utter bullshit because Trump hit the ground running with the obnoxious insult machine stuck in high gear when he first entered the Republican primary.
It's his brand.
His trademark.
He adopted it because he knows that insults are exactly what the hard core right wants to hear.
But it has nothing to do with the way anyone else treats him.
You missed the entire point. Each side justifies their trash talk because they said the other side did it first. It doesn't matter who really started it (it was long before Trump), it is that each side continues the juvenile feud.