They've managed to convince enough people to vote against their own self-interest by appealing to fear, ignorance, and hate. Apathy, voter suppression, redistricting, gerrymandering and the electoral college did the rest.

All that really matters to them is

1) Taxes (PARTICULARLY capital gains and corporate) go down or are repealed.

2) Health, safety, worker and environmental regulations on business are pulled waaaaay back or repealed.

3) Social services are shutdown and the New Deal rolled back.

4) Government worker unions are crushed (they've already succeeded with the others).

5) Unemployment is kept as high as possible, which will keep salaries down.

6) Illegal immigration is kept high enough that cheap and docile labor is always available for agriculture and service jobs. The Wall won't stop anybody, they'll come in planes, trains and automobiles.

7) Inflation takes off (So they can borrow today's dollars and pay back in tomorrow's), while the value of Capital (property, tooling, facilities, commodities and equities)
rises automatically with inflation.

Of course, they're not publicizing 5), 6) and 7), but that's the inevitable result of their other policies.
As for whatever damage results from these policies, they simply don't care. They'll have the financial resources to ride them out comfortably. The rest of us won't.

Trump is a problem, though. His incompetence is so total and obvious it can not be disguised or ignored much longer. His usefulness is quickly coming to an end. You will soon see him removed, by his own party, and a more traditional Republican like Pence, one with traditional Republican goals, will take his place.

That's what really worries me.