There are a few scenarios. One would be Chinese companies are forced to get more efficient to survive. This makes them even more competitive and they can force out American companies in other contested regions.
Another is the inflation caused by the tariffs reducing the profits of industries that compete for the same consumer dollars. If consumers are paying more for plastic goods, then they have less money to spend on discretionary purchases.
Production moving from China to the US puts strain an already tight labor market, which displaces incumbent industries. I.e., shoe manufactures move to the US to avoid tariffs, which makes labor too expensive for the cardboard industry, who moves to another region.
All of these effects cascade to related industries.
Also, the collective "we" can win even if a large number of us suffer as a result of these policies.
Trade is usually 'win win'. So when there's less trade, there's less 'winning' on both sides.
Imagine if Chia is the sole source of Silk, and the US is the sole source of Rubber.
If the US 'wins' a trade war with China by doing more damage to then, but there is less trade ... well then there is unmet/latent demand in the US for Silk and in China for Rubber that is not met, which is an economic loss.
That said - trade needs to be in fair terms or it doesn't work. If one side cheats, they can suck all of the 'win' out of the 'win win' for themselves.
