I'm not saying he's doing this, but if you announce a tariff, and the stock market tanks, it is cheaper to buy more stocks... Then wait until the rebound to sell.
However, a day ago, the Trump reversal didn't save the stock market. https://www.msn.com/en-us/money/markets/stock-market-today-trump-s-tariff-reversal-can-t-save-stocks/ar-AA1ApkHl
That may not be his plan, but his "I'm going to effect a tariff... PSYCH!" really doesn't make a lot of sense. Unless it's a buy low, sell high strategy, I am at a loss for what he is doing.