Are you really ok with the U.S. potentially losing its uncontested power status?

The U.S. pulling out of international cooperative bodies / agreements / aid will likely mean another power will step in and have influence.

The U.S. angering and threatening allies and acting in unpredictable ways will likely lead to more countries arming themselves, some with nuclear weapons. I understand this is what conservatives wanted them to do so that we don't shoulder the burden of policing, but is this really a good idea? You can't expect these countries to be benevolent forever, given that humans have a history of grabbing abusing power (eg nukes) once they have it?

The U.S. acting unpredictably in trade will encourage nations to diversify away from the U.S., while creating closer ties with other nations. It may create greater solidarity in the EU to bargain against the US. Some nations will consider diversifying away from the USD. The USD and debt debt will no longer be considered reliable, further limiting our options for responding to economic crises (borrowing more, printing money).

America First sounds a lot like isolationism and it seems like that's the goal. We have power now and can throw it around, but what happens when we no longer have that? We will be at the mercy of those that do, and they will be happy to bully the U.S. Things aren't perfect right now, and it sucks to pay taxes to police and help the world, but aren't the alternative possibilities significantly worse?