Did you looked at Forex few hours before tarif announcements against Brazil (BRL vs USD) then few days later with the EU (EUR vs USD)?

You're looking at the wrong board despite thinking about the same game.

This is part of the answer.

The clearer answer is: the US stock market is denominated in dollars.

If dollars devalue, then the price of real assets and equities in dollars increases (i.e. equivalent value, different number).

It's entirely possible two things happen at once: (1) US companies become less profitable and competitive due to tariffs (thereby decreasing their objective value) & (2) US dollars devalue (thereby increasing assets value in terms of US dollars).

Realistically, persistent inflation, international willingness to buy US government debt, and/or consumer confidence will be the things that collapse everything. (Or not)