The 100-day reviews are in, and they’re terrible. The health care faceplants just keep coming; the administration’s tax “plan” offers less detail than most supermarket receipts; Trump has wimped out on his promises to get aggressive on foreign trade. The gap between big boasts and tiny achievements has never been wider.

Yet there have, by my count, been seven thousand news articles — O.K., it’s a rough estimate — about how Trump supporters are standing by their man, are angry at those meanies in the news media, and would gladly vote for him all over again. What’s going on?

The answer, I’d suggest, lies buried in the details of the latest report on gross domestic product. No, really.

For the past few months, economists who track short-term developments have been noting a peculiar divergence between “soft” and “hard” data. Soft data are things like surveys of consumer and business confidence; hard data are things like actual retail sales. Normally these data tell similar stories (which is why the soft data are useful as a sort of early warning system for the coming hard data). Since the 2016 election, however, the two kinds of data have diverged, with reported confidence surging — and, yes, a bump in stocks — but no real sign of a pickup in economic activity.

The funny thing about that confidence surge, however, was that it was very much along partisan lines — a sharp decline among Democrats, but a huge rise among Republicans. This raises the obvious question: Were those reporting a huge increase in optimism really feeling that much better about their economic prospects, or were they simply using the survey as an opportunity to affirm the rightness of their vote?

Well, if consumers really are feeling super-confident, they’re not acting on those feelings. The first-quarter G.D.P. report, showing growth slowing to a crawl, wasn’t as bad as it looks: Technical issues involving inventories and seasonal adjustment (you don’t want to know) mean that underlying growth was probably O.K., though not great. But consumer spending was definitely sluggish.

The evidence, in other words, suggests that when Trump voters say they’re highly confident, it’s more a declaration of their political identity than an indication of what they’re going to do, or even, maybe, what they really believe.

May I suggest that focus groups and polls of Trump voters are picking up something similar?

One basic principle I’ve learned in my years at The Times is that almost nobody ever admits being wrong about anything — and the wronger they were, the less willing they are to concede error. For example, when Bloomberg surveyed a group of economists who had predicted that Ben Bernanke’s policies would cause runaway inflation, they literally couldn’t find a single person willing to admit, after years of low inflation, having been mistaken.

Now think about what it means to have voted for Trump. The news media spent much of the campaign indulging in an orgy of false equivalence; nonetheless, most voters probably got the message that the political/media establishment considered Trump ignorant and temperamentally unqualified to be president. So the Trump vote had a strong element of: “Ha! You elites think you’re so smart? We’ll show you!”

Now, sure enough, it turns out that Trump is ignorant and temperamentally unqualified to be president. But if you think his supporters will accept this reality any time soon, you must not know much about human nature. In a perverse way, Trump’s sheer awfulness offers him some political protection: His supporters aren’t ready, at least so far, to admit that they made that big a mistake.

Also, to be fair, so far Trumpism hasn’t had much effect on daily life. In fact, Trump’s biggest fails have involved what hasn’t happened, not what has. So it’s still fairly easy for those so inclined to dismiss the bad reports as media bias.

Sooner or later, however, this levee is going to break.

I chose that metaphor advisedly. I’m old enough to remember when George W. Bush was wildly popular — and while his numbers gradually deflated from their post 9/11 high, it was a slow process. What really pushed his former supporters to reconsider, as I perceived it — and this perception is borne out by polling — was the Katrina debacle, in which everyone could see the Bush administration’s callousness and incompetence playing out live on TV.

What will Trump’s Katrina moment look like? Will it be the collapse of health insurance due to administration sabotage? A recession this White House has no idea how to handle? A natural disaster or public health crisis? One way or another, it’s coming.

Oh, and one more note: By 2006, a majority of those polled claimed to have voted for John Kerry in 2004. It will be interesting, a couple of years from now, to see how many people say they voted for Donald Trump.