This is a good point. Rationally, the US government exists solely for the purpose of advancement of the interests of the American people. However, trade wars are NOT in the interest of the American people either; free markets are. We don't even need to theorize about this, there has been an actual drop in illegal immigration from Mexico because of its rising prosperity. So the rational conclusion should be to continue down this path, as it seems like the only solution that seems to really work.

Also, it is not at the cost of American jobs; of course those specific jobs are lost, but unemployment is down, private sector is adding thousands of jobs etc.