User tomi000@lemmy.world gave me the best explanation when I asked what the rationale is for Trump's tariffs:

His logic is: I walk into a store and buy a hat for 10$ and sell them a shoe for 7$. This means the store ripped me off by 3$. To counter this, I will add a tarriff of (3/10)/2 = 15% to all business I do with this store so they dont dare sell me anything in the future.