Jesus. Here it is again in 8th grade terms, so you can understand. Trump is a candidate, who doesn't have the same level of protection as an actual President. We have a long history in this country of trying to kill "outlier" candidates. Trump certainly qualifies.
I don't want to see anyone hurt, but Trump's rhetoric has numerous groups very angry with him, making it very possible they might want to get rid of him.
You have more than enough crazies available in the GOP already, even before Trump became an issue.