The market is supposed to be objective and motivated only by profit but these decisions are informed by the biases of those people. Worse, it's deeply informed by what those few thousand wealthy people *think* their peers will do.
So you have people saying "no one believes Trump when he says the war is over, but we expect the market to react to what he says so we will react in anticipation of that... thus creating the reaction."
But, this doesn't go on forever.
At some point what the president says will become irrelevant to the market. His words are already irrelevant to many people, and to many nations because he simply lies far too often. It's like making investment decisions based on the output of a fortune cookie.
The previous observation that the market would be tanking with a democrat in office is based on similar circular logic. "we expect everyone else will pull out so we will move first"
I think there is something deeper at work as well. The thousands of wealthy people who make up the market see Trump as someone who protects their interests. If there is economic pain they expect that he will shield them. This is how many of the ordinary people who support him see it as well.
Both of them are being naive and duped. There is only one person Trump cares about. He might care a little more about rich people, but only because he's a member of that group.
The market is just like a place where rich people get to vote based on how rich they are and the extent to which we allow it to drive policy and decisions is anti-democratic in the one person one vote view of the world.
"Listen, Smaug, is it OK if I just call ya 'Smaug' ? ... "