They should have voted to prevent this, but only half of them did. They other half lived through the first Trump admin and decided that it was not worth a few minutes of their time to prevent it. They didn't have to cross an ocean or fight a war... they needed to visit a website to get registered and the mail a form (or stand in line for a while) to vote, and they didn't.

In other words, only 1/3 of Americans voted against this.