When the markets are down, they are on sale for the rich. Eliminating competition via tariffs is good for those who want to compete where they couldn't before. They would let everything burn to further enrich themselves or push their ideology.
Why are they only on sale for the rich? I thought everybody could buy it. When Wall Street Bets was buying GameStop was that an investment "for the rich"? And if not why can only rich people invest when markets are down, and only not rich people can invest in GameStop when they are being short squeezed?
I think the combination of malice and incompetence remains the most credible theory:
Trump believes that the he/the US has the more powerful position in all of these relationships and wants to impose his will on the rest of the world and make them submit to his/US superiority. Which might actually work if he picked one target at a time. But you can't beat up the whole school at once. The fact that he can't do this to everyone at once, combined with his utter misunderstanding of what trade imbalance actually means, will lead to an outcome that is bad for everyone, but worse for the U.S. than most.
There are two other theories that I think have some shred of credibility, and they're both worse:
1. Trump intends to use his apparent ability to unilaterally impose or negate these taxes at will on a granular level to force countries, companies, and individuals to come groveling to him for favors, allowing him to use the presidency to further enrich and entrench himself.
2. Trump is divesting of dependence on allies because he thinks they might soon be adversaries. That's the most harrowing potential interpretation, but it relies on the notion that he has any kind of foresight. This is really only credible if you genuinely believe that it's Putin pulling his strings. Which is a possibility that's hard to dismiss.
@2) I don't see Putin behind this. The current situation is most likely a death stroke for Russia. Russia's war economy was already on the brink and running on borrowed time. With oil prices cratering that's it.
