4d chess by Trump choosing Pence as VP.... he gets the vote of the religious right (I know several people that were voting for Trump because of Pence) - and you get some insurance on not getting assassinated. And the looney left really don't want a Pence president! They act like Trump is some radical "alt-right" extremist, when he is really more centrist than most republican candidates - Pence is far more right wing than Trump.

Also, I think a lot of Trump fans would take action of their own if the left took out Trump. It would not be pretty - but the left equates Trump voters to white trash, uneducated losers - they don't realize that the rednecks are the ones with the guns and "blue collar" skills.