The axiom, follow the money, is always relevant. It was true when it was coined with regard to Nixon. It is even more true in contemporary times.
I've long said that marijuana will be legal nationwide within the next 10 or so years. Follow the money. It is now more profitable to elected officials to vote in favor of those producing and selling it and say its all for tax revenues than it is to fund the DEA against it. The size of the budget of the DEA does not get individual congress critters re-elected. Nor do fines and prison sentences for the use of something the public clearly knows is less harmful than alcohol. The donations from people in support of legalization do get them re-elected. Those are the people who will be the winners.
How this relates to Trump is simple. He was useful up until the time the Congress passed the tax cut. By then, he had also already appointed enough ALEC-loving, right wing judges to the courts so ALEC, the chambers of commerce, etc. are very much ahead for the next generation or more.
Now, we've entered the time of diminishing returns. He's no longer worth supporting. In fact, he's begun to cost them money. It is simple math. If he cannot deliver on $$ then he's not worth them supporting. His tariffs and chaos causing uncertainty in the markets cost them money.
He will go down. Exactly how is still a great question. But he's served his purpose and has exceeded his usefulness to those who put in him office.