Then don't take my word for it. Here's what the father of economics and of capitalism, Adam Smith, has to say:
It is the maxim of every prudent master of a family, never to attempt to make at home what it will cost him more to make than to buy. The tailor does not attempt to make his own shoes, but buys them of the shoemaker. The shoemaker does not attempt to make his own clothes, but employs a tailor. The farmer attempts to make neither the one nor the other, but employs those different artificers. All of them find it their interest to employ their whole industry in a way in which they have some advantage over their neighbors, and to purchase with a part of its produce, or what is the same thing, with the price of a part of it, whatever else they have occasion for. What is prudence in the conduct of every private family can scarce be folly in that of a great kingdom.
Or, believe the more than 1000 economists who tried to warn Hoover not to sign Smoot-Hawley plus a few who are trying to give the same warning to Trump:
https://www.wsj.com/opinion/a-lette...tariffs-policy-protectionism-economy-9a063b69