Trump is not destroying the Republican Party. He is embracing it.

[The Magistrate]

5. True, Sir

Originally the country-club types thought they could rouse up the rubes, while remaining in charge and doing nothing the rubes really wanted. But the rubes they roused up to vote began to get themselves elected to state legislatures, and then to Congress and the Senate. The genteel, paternalistic racism of the country-club types has been overwhelmed by the raw sewage of the rubes who honestly feel they haven't much claim to self-respect beyond 'being white'. And the intelligence and rationality the country-club types could display, especially in a crisis, has no footing at all in the squawks of the rubes, whose motto is Mr. Asimov's observation years ago, that many here believe democracy means 'my ignorance is equal to your knowledge'.

Trump, ignorant, blinkered, not awfully bright, impulsive, vindictive, and downright mean in every sense of the word, embodies both everything the rubes are, and everything the rubes aspire to be. Certainly if they were rich, they're sure they'd be just like him.