The problem with this line of short term thinking is that it can backfire badly. Yes, they get 1 term or 2, but then the backlash can bury them for decades. Especially in the context of America's changing demographics.
It's not short term thinking at all. This is the GOP's big chance to roll back the modern American system, which was erected by liberals like Roosevelt and Johnson, and replace it with something more to their ideological liking. Doing so has been their #1 political objective since the 1930s.
Why on earth would they fail to seize such an opportunity? Especially when, as you note, changing demographics mean that another one is unlikely to ever come again?
Why on earth would they fail to seize such an opportunity? Especially when, as you note, changing demographics mean that another one is unlikely to ever come again?