The question is: how did this happen? Jon Chait describes the remarkable reality perfectly:
The general operating method of Republican politics is to use ethnonationalist resentment to generate support for elite-driven anti-government policy. That is, there is one basket of issues Republicans use to harvest votes — talking tough against communists or terrorists; defending the flag; posturing against criminals; getting tough on welfare cheats — and then the different basket of policy objectives they spend their political capital on — tax cuts for the rich, deregulation for business.
This is the fact that must be explained. This is the truth that must be understood. It is extremely odd.