I think it stems from the American Exceptionalism idea. Before people jump down my throat, I'm not saying America isn't great. But there is a prevailing idea that we are the country of "bootstraps." Everyone likes to take credit for making something out of nothing on their own without any help while conveniently ignoring all the people and institutions that made their journey up the ladder possible. That goes back to isolationism. It's really a delusion that we don't need anyone else because we did it ourself before and can do it again....except we didn't do it ourselves. We had the help of European allies. And if the shipping bottleneck and computer chip shortage in no small part helping to drive up inflation is any indication, we absolutely need imports and exports to keep our economy moving. Locking down would destroy our economy.