Two years ago, after the shock of Donald Trump’s election, financial markets briefly freaked out, then quickly recovered. In effect, they decided that while Trump was manifestly unqualified for the job, temperamentally and intellectually, it wouldn’t matter. He might talk the populist talk, but he’d walk the plutocratic walk. He might be erratic and uninformed, but wiser heads would keep him from doing anything too stupid.

In other words, investors convinced themselves that they had a deal: Trump might sound off, but he wouldn’t really get to make policy. And, hey, taxes on corporations and the wealthy would go down.

But now, people are realizing that there was no such deal. Put an unstable, ignorant, belligerent man in the Oval Office, and he will eventually do crazy things.

To be clear, voters have been aware for some time that government by a bad man is bad government. That’s why Democrats won a historically spectacular majority of the popular vote in the midterms. Even the wealthy, who have been the prime beneficiaries of Trump policies, are unhappy.

But market behavior has, until recently, been a different story.

The reality that presidential unfitness matters for investors seems to have started setting in only about three weeks (and around 4,000 points on the Dow) ago. First came the realization that Trump’s much-hyped deal with China existed only in his imagination. Then came his televised meltdown in a meeting with Nancy Pelosi and Chuck Schumer, his abrupt pullout from Syria, his firing of Jim Mattis and his shutdown of the government because Congress won’t cater to his edifice complex and build a pointless wall. And now there’s buzz that he wants to fire Jerome Powell, the chairman of the Federal Reserve.

But let’s play devil’s advocate here: Does all this Trump chaos matter for the economy, or for the stock market (which isn’t at all the same thing)? At first sight, it’s not all that obvious.

After all, aside from the prospect of trade war, none of Individual-1’s tantrums, unpresidential as they are, have much direct economic impact. Even the government shutdown will impose only a modest drag on overall spending.

So why do investors seem to be losing their what-me-worry attitude? It’s not so much what Trump is doing, as what he might do in the future — or, perhaps even more important, what he might not do.

The truth is that most of the time, presidential actions don’t matter much for the economy; short-term economic management is mainly up to the Fed. But when bad things happen, we do need the White House to step up. In 2008 and 2009, it mattered a lot that officials of both the outgoing Bush administration and the incoming Obama administration responded competently and intelligently to the financial crisis.

Unfortunately, there’s no reason to expect a comparable degree of competence if something goes wrong again.

Consider how the Trumpistas have responded to falling stocks. So far these are just a minor economic bobble. Yet Trump himself, having claimed credit when stocks were rising, has flown into a rage and lashed out; hence the attacks on Powell. Meanwhile, top officials are still claiming that last year’s tax cut was a triumph in the teeth of the evidence, and issuing bizarre statements — via Twitter — about the health of the banks, which nobody was questioning.

Now imagine how this administration team might cope with a real economic setback, whatever its source. Would Trump look for solutions or refuse to accept responsibility and focus mainly on blaming other people? Would his Treasury secretary and chief economic advisers coolly analyze the problem and formulate a course of action, or would they respond with a combination of sycophancy to the boss and denials that anything was wrong? What do you think?

Let’s be clear: There isn’t an obvious crisis-level threat looming at the moment. But growth is slowing, and as the bumper stickers don’t quite say, stuff happens. And if and when it does, the people who would be supposed to deal with it are the gang that can’t think straight.