Turns Out Appeasing Trump Only Emboldened Him

Well, yeah - he's a stereotypical bully (just notice how he uses the threat of lawsuits to bully small contractors supplying his companies which he doesn't want to pay) and those invariably see appeasement as proof of the weakness of the other side and will double down on the bullying if they get concessions to extract even more.

Bully, get concessions, bully some more, get more concessions, bully some more, get more concessions and so on is a pretty standard process for bullies.

The way to deal with bullies is to do the exact opposite of giving concessions: go in the very opposite direction and fuck them up, don't just respond in kind, respond with a more hurtful response than their original action. If they react to this by pushing harder, push them back even harder and they always end up backing down, especially if they can come up with some bullshit to save face: China has perfectly demonstrated this process with Trump's tariffs.