The lose USA is going to experience won't be like a regular war where you kill and get killed.
It will be a financial one. Free hint for you: Gold.
If you think USA will stay king forever by printing FIAT then you must be high. Sooner or later bubbles will start popping and USD will be a dead currency. (it is already dead tbh, we are playing the extensions)
Not at this rate, Trump has been slowly cutting back on the National Debt. If things continue at this rate USD wont be collapsing any time soon.
No one is underestimating the US Dollar. Other currencies such as the Euro and the CNY have been trying to displace the USD as the currency of international trade for quite some time now. But they have failed miserably.
Actually @mindrust was. A lot.