I think it's not clear whether the MAGA politicians are rational or not. Clearly, many of them know little about the government of states, which explains why there is so much fumbling about and obvious mistakes and unintended consequences. However, it's clear that Trump is a con artist. He is using the power of the presidency for personal gain. Just now there are videos showing how Trump is bragging about how he and his friends made a lot of money by taking advantage of the stock market fluctuations caused by Trump's tariffs (being turned on and off). This is entirely rational behavior from a con artist and a narcissist. He's got the all-clear from the Supreme Court that he can't be held responsible for his official actions as president in court. Congress could still hold him responsible (impeachment), and the people maybe can (if there are free elections in the future) but it could very well happen that he gets away with it, and he's old enough that even if he does go into prison, he wouldn't be there for a long time.
Tariff wars tend to be followed by actual wars where people die. That's why the EU was founded, by removing tariffs between European states, it was thought that wars between the states can be avoided, which has been the case so far. However, for Trump, the tariffs are just a means towards personal enrichment (and his friends' enrichment), plus getting a lot of personal attention in the media that he craves.