Tariffs are appealing to him because they are incredibly forceful blunt instruments over which he alone has almost complete control. They give him immense, immediate influence over the entire world. What we're seeing is that the US President today, if the full capacities of that office are pushed as far as possible without violence, is arguably one of (if not the) most powerful human beings ever.

Beyond this, Trump has said that one of his greatest weapons is uncertainty. He wants to be feared. Having people genuinely afraid of you is the next step of power that he is already flirting with by posting videos of people being blown up in warfare on social media.