Another reason is that being economically dependent on foreign countries can be quite risky. E.g. if China gets economically independent from the west but the west is still dependent on China, China will have immense power over the west.
Trade makes everyone richer, and the cost is that some of the people you don't want to be rich get rich. But willfully choosing to be poor doesn't fix that.
They aren't doing it for economic purposes but for political ones: They are nationalist authoritarians; tariffs are not only nationalistic policy, they undermine international institutions and cooperation.
> if Trumps turns over the reins of government to a bunch of technocrats
That seems like the opposite of Trump's behavior, campaign promises, and plans.
I'm choosing this moment to try to be optimistic: if Trumps turns over the reins of government to a bunch of technocrats... it's not the worst possible thing that can happen.
The real question is who's going to restrain him from turning the DoJ into a revenge organ. The rule of law is historically very hard to get back once its lost.