To answer the topic's question, let's use a simple analogy - a manufactured screw driver:-
USA has all the mineral resources it needs to produce products for consumers, more so for its own citizens.
The USA manufactured screw driver would cost only mere 20cts based upon material costs alone, but sold at USD$1 each. That other 70cts is to cover workers' salaries, factory space, overheads, marketing as well discounts to distributors.
USA is a population of 300million & the screw driver is a basic essential tool used in every household, thus with population growth, that mere tool would generate millions annually. It is just one tool, amongst many MANY more other tools.
China, while may not be as resource rich as USA, can easily make the same tool, with far lower overheads - cheap labor sweat shops, boundless factory spaces, etc with even well known cutting corners, & dump such products into USA at 70cts.
As such, the USA manufacturer of screw drivers will have to close shop as no American will buy its $1 product, leading to a cascading effort of retrenchments not just at the manufacturing plant, but even to USA supply chains, even right down to the mom & pop shops or restaurants as most would be out of jobs to afford anything.....
Thus there is a need for protectionism, to protect a nation's employment & economy. With a rather small tariff of 70% on the sale of one China made screw driver, it will cost an American to buy it at $1.20cts, compared to a USA made that cost $1. One can only get rich by saving & smart expenditure, thus with such a move to buy American, it will save American jobs, employment & economy.
Should Americans still insist on buying poorly made China goods, which looks good but will not last, even their EV cars, each 50cts of Tariff will go into USA Treasury to fund social expenditure, such as health, education, infrastructure, etc...
Thus, it proves 50.7% - 73 million +American voters were not foolish whom voted for Mr Trump, among many other promises he made to the voters to make America great again, against the other 47%.....