I'm trying to think of equivalent items that one would do when opting out of citizenship that are equivalent to emptying out the health spending account when you quit a job to try and make your money back.
As for my own opinion, Trump's actions have improved the situation somewhat but perhaps only temporarily. The reporting requirements remain onerous, as the IRS effectively intrudes into every aspect of your life through financial inspection - it is an absolute violation of everyone's humanity and rights, regardless of income level.
The United States had no income tax or reporting requirements for over a third of its existence and experienced growth; now that the tide has shifted, the US tax requirements would be causing a much greater exodus if it weren't for the fact that there are not currently many places worldwide in a better position.
[1] https://www.forbes.com/sites/robertwood/2015/10/23/u-s-has-w...
I believe that the initial taxation was for import/export, but that's also a time when the social welfare state didn't exist. Though the first income taxes came along to pay for war - I guess all the United States needs to do is stop being in the business of war and the income tax could go away. Any day now.
The first income tax came to pay for the Civil War; I don't think the US is going to give up on maintaining it's territorial integrity, even if it gave up on foreign wars.
It would also seem to be a very hard line to draw in regards to "preventing external threats". An argument could be made that that's exact what's happening right now, and that it's aggressive posture and presence around the world is solely in self defense, so really, the industry of war probably can't ever stop, and neither can the income tax.
That's true because of the income tax derived funds lavished on the US Army (and other branches.)
Were that to stop—which abandoning the income tax without a similar scale replacement would likely require—other options would rapidly open up.