To play devil's advocate
1) trumpers feel that a extra bit of economic growth is worth having a corrupt president. Senator Hatch said this, explicitly, but almost all Rs agree.
2) trumpers feel that there is an egregious double standard - that only Rs are prosecuted and not Ds. That anger at perceived injustice has made them into miscreants. 'Oh yeah, you think i'm a bad guy? Ok, I'll show you bad guy, Mofo.'
3) Trumpers are deeply attracted to bigger than life political personalities. They want a big man, doing big things. They laugh at technocrats like Obama and HRC - people who rely on facts and detail. Trumpers want the big sweeping idea, not the boring execution.
4) Trumpers feel Trump will find a way out, like Bill Clinton found a way out.