Trump encourages the violent behavior of the supporters who attend his rallies.

He still has supporters because most of them are mature enough to realize that a couple of malevolent a$$holes don't represent the man or his putative 'movement.'

But they do because he supports them

How does he encourage it?

He's been caught so many times at his rallies, saying things about protesters like "I'd like to knock the crap outta that guy", "In the good old days, they'd carry him out on a stretcher", "I'll pay for your legal bills", etc. At least one guy sucker punched a guy being escorted out, at one of these rallies, after Trump had made these kinds of comments. That's how he does it. Not to mention the increase in attacks agains Muslims, Latinos etc that has occurred since Trump started his anti-Mexican, anti Muslim rhetoric publicly. Come on, you know this stuff already.