From my perspective it seems clear that the American public has been in the grips of anti-intellectualism for quite a long time. In 1980 Asimov made the following famous statement:
There is a cult of ignorance in the United States, and there always has been. The strain of anti-intellectualism has been a constant thread winding its way through our political and cultural life, nurtured by the false notion that democracy means that “my ignorance is just as good as your knowledge."
For the record, I'm not American, and not anti-intellectual.
Here's a better example of patronizing by experts from the current crisis: "The average person should not wear a mask. Not only it doesn't protect against the virus, but it actually may harm."
What they mean is: it may harm by giving a false sense of certainty. Clearly the average person is too stupid to understand the difference between perfect protection and "not quite perfect, but better than nothing" protection.
In your Iraq war example I don’t recall bureaucratic experts being involved in support of it. General Shinseki famously thought Rumsfeld’s predictions were wrong and Hans Blicks (spelling?) was famously skeptical of Bush administration claims.
I’ll certainly agree that we’ve had crappy political leadership in the U.S. but I won’t agree that bureaucrats have let the nation down in matters of science. Experts get it wrong and consensus expert opinion is sometimes wrong. There will continue to be examples of where consensus expert opinion is wrong.
You can find individual experts who are patronizing and lecturing as you put it. It’s been rare in my experience that consensus expert opinions that aren’t motivated by money, greed, power, or fame are condescending or lecturing.