There are plenty of jobs. Every person who isn't manufacturing is a person who can do something else. A modern car uses a lot more engineers. While we don't need many spa mangers, it is nice that spas exist and so some of those spa managers are needed.
Long term, manufacturers will come back or be created to grab all those customers. But for the rest of the world, it's much harder for suppliers who lost a massive chunk of their customers to suddenly find new customers beyond what's already existing. Creating demand is notoriously harder than increasing supply. And it dosen't help that the majority of other major economies are also export-based, so unless if some are willing to run deficits (and they won't), there's literally nowhere else to go other than a global recession. Developing countries are far too poor and would essentially be turned into captive markets bereft of industrialization.
I don't agree with the implementation of Trump's policies, but this is going right back to Keynes' concerns about limitations of global trade balancing, it's a long time coming, and much of the blame does come back to the surplus economies that doubled down on manufacturing rather than transitioning to consumer based economies.
Is it controversial to say that if you really wanted to "fight the oligarchy", your policy positions would be pretty similar to the America first agenda (sans social issues)?
If they call out the active duty military against middle-aged, white, protestors, they'll have a problem. If it's against students and minorities,...
"There's a Homer Simpson quote that I like for thinking about this. It's just something that Homer blurts out when someone's talking about someone who lived 150 years ago. He says, "If he's so smart, how come he's dead?" When faced with expertise, they'd be like, "Well, if he's so smart, how come he's poor?" They believe that everything can be quantified, like the utilitarian dream, the eugenicist's dream, a person's IQ, and that money is a good measure of how much someone is worth. So they must be the best and smartest and greatest people who have ever lived."