Putting aside the fact that tariffs became disastrous in the highly interconnected world of the 20th century, tariffs traditionally have three goals:
Raise revenue for the government.
Discourage the purchasing of foreign products and encourage buying domestic.
Fund domestic manufacturing and national infrastructure.
All three of these create a system where taxes are hiked on everyone, but in a way even the poor can accept, so long as the purchasing of domestic products remains cheaper and the revenue is used to pay off the national debt, create jobs, and repair crumbling infrastructure.
However, the GOP is against deficit-reduction since they’re the party that increases it the most, and generating a surplus would rob them of something they can complain about whenever the Dems are in power, just like how permanently securing the border would see the GOP lose something they can always get white people enraged about. The GOP might want to encourage domestic consumption, but even that claim’s doubtful since they also want to hike sales’ taxes on domestic goods, they don’t want to bring jobs to the US unless the American worker is willing to be worked harder and paid less than someone in a Bangladeshi sweatshop, and (as said earlier) the GOP thinks building anything the rich don’t need is a waste of resources; why build bridges in all the rural states they claim to love (but actually consider to be losers) when that revenue can be stuffed directly into the pockets of the rich?
Trump’s just trying to implement the GOP’s harebrained scheme of a radical tax reform that’ll allow even more money to be redistributed to the billionaire class, and the rich are mad at him because they feel he overstepped and moved too far and too fast into the project.