“He’s at the peak of just not giving a f--- anymore,” said a White House official with knowledge of Trump’s thinking. “Bad news stories? Doesn’t give a f---. He’s going to do what he’s going to do. He’s going to do what he promised to do on the campaign trail.”
Basically first time around Trump wanted to do this and his advisers told him it would be a disaster. Navarro did come up with a formula but in the end they didn't do it. This time around he used Navarro's formula, which is why you see Peter in the news touting the tariffs, it was his formula. his advisers had spent most of his new term working on multiple options, and then Trump ignored all of them and implemented this one on his own. The final decision was made 3 hours before he presented it, none of the advisers who'd worked on the plan expected this to be the choice but Trump no longer cares he's only listening to his own voice now.
https://archive.ph/NDUaS#selection-705.0-705.261