Easy: it didn't happen in a democratic country.

In his previous term there were people in all positions that would say no. He didn’t like that and fired people constantly, rotating through an inordinate amount of staff.

This time round they pre-planned everyone in every inch of federal government. All loyalists. No one will say no. They all fall in line and do as they’re told.

Trump and his handlers will strip mine and destroy the country from top to bottom completely unchallenged. And any challenge will simply be sidestepped or simply ignored.

The dams are entirely the responsibility of the Army Corps of Engineers, and the US President is the commander-in-chief.

The only ways for this to not happen is for the President to have their mind changed, or the President is removed from office, or, the order is refused enough (at cost of being fired/court-martialed) that nobody will carry them out.

The great powers of the US Presidency is meant to expedite government action. We are currently far from the scenario where Congress, by the will of the US voters, will remove the current President.

We have three branches in the federal government - executive, legislative, judicial. Legislative creates laws. Judicial basically decides when they apply/arbitrates their implementation. Executive branch is the actual meat of the entire thing, containing basically every other federal government institution, which is (in broad strokes) a giant hierarchy with the President at the top, with the ability to override every decision. It's because the people who designed this system had monarchism as their primary frame of reference and basically designed "monarchism with a couple restraints". People like to think it's democracy with checks and balances, but the democratic elements are worthless and the checks and balances have completely failed.