Yes, it's a cult of personality. There's nothing rational about it.
To be fair, I've seen some of that behavior among Trump supporters, even here on FR. But, it's much less pronounced -- and in most cases it is less pro-Trump and more anti-GOPe.
While I don't think it's productive for Trump to antagonize the GOPe, I do think he should try to tap into the disgust with the "Uniparty". There is a huge bloc of people that don't vote simply because they are dissatisfied with the choices offered by the major parties, and think voting for a third party is a waste of their time. If Trump can tap into that group and bring even a small percentage to the polls in November -- especially in the battleground states -- he can sew up the election.
Someting like 60 PERCENT don't vote for exactly those reasons. And I believe a lot of them are VERY interested in The Donald. Even ten percent of them make it a blowout.