Comment by Terr_

They'll work their way up to anti-constitutional attacks on everything else if they get a chance, USAID is their starting point because it's a softer target in a few ways:

1. The people who'll suffer or die from their mal-management will generally be faraway foreigners, as opposed to people voters know.

2. More of the victims have a much more difficult time launching any kind of lawsuit in US courts.

3. It has a small veneer of Presidential-involvement-ness due to its proximity to diplomacy and foreign relations.

4. Like tariffs, being able to withhold aid allows Trump to commit extortion against other countries, much like how he was impeached for extorting Ukraine in his first term.