The older generations in the US are demonstrating fluid intelligence by being manipulated to support actions and ideology they would never have condoned in the past and coming up with stunningly complicated rationalizations. And the manipulation is through newer avenues like social media. They keep moving further and further into alternative avenues like youtube and Facebook alternatives that maintain their preferred echo chambers. These people are now able to find millions that agree with them and it it is self reinforcing even without FB's algorithms so that they become increasingly extreme.