So what, Reagan was senile and he may have been the most successful president of the 20th century (FDR won World War II, but in a way that resulted in a Cold War lasting almost 50 years).
And under the Constitution, policy making is done by the Congress, which is hopelessly divided, meaning they can do nothing (not such a bad thing) or learn to “play well with others” (also not so bad). The stock market seems favorably impressed with a government that will be unable to get into mischief, or even better, learn to cooperate rather than be fixated by ideological idiocy.