It's why the loss we saw yesterday wasn't as bad as many thought over the weekend. They clearly believe that this is some game of chicken and a deal will be reached.
None of this saves the market long-term but it gives runway in the short-term before anything is finalized and implemented permanently.
Ironically, the market's tepid reaction to Trump's tariff rhetoric is probably helping him dig in even more since we've yet to see the type of collapse that fuels massive panic (the 2008 crash saw a loss of 8% on October, 15, which at the time was the largest percentage decrease since Black Monday - and before that, the Great Depression).
There were multiple other days with 7% losses.
Right now, the decline we've seen hasn't even managed to break into the top20 all-time in terms of percentage (total points is misleading as the stock market is much higher today than, say, 20 years ago).
So, Trump probably believes he can weather this storm ... until the markets realize there will be no deal and he's set going forward. But even that could be muddied as the markets assume after the tariffs go through that they only last for weeks/months before they're reversed for some reason.
Clearly the markets are acting from the perspective that these tariffs will not go through in their current capacity. Problem is, there's no reason to believe this and the market response isn't devastating enough at the moment it seems to scarw Trump or Republicans away from the ledge. That's not good.