That whole ‘so you can have it all’. Nope, not at the same time. That’s a lie,” said Michelle Obama. “And it’s not always enough to lean in, because that s*** doesn’t work all the time.”

The crowd at her Saturday night book-tour stop were already hanging on every word, but this line set them alight.

A former First Lady saying the s-word will always cause a stir, and Obama quickly apologised — “I forgot where I was for a moment!”

But the excitement was for something else, too — a jolt of affirmation. The audience in Brooklyn’s Barclays Centre, and the younger fans who endlessly shared and retweeted the moment, felt the delight of having their feelings seen and recognised, and their disappointment validated.

Obama’s reference to “leaning in” called out Sheryl Sandberg’s 2013 book and the movement it sparked. On the heels of the Great Recession, the Facebook chief operating officer encouraged young women to follow her example.

Lean In: Women, Work, and the Will to Lead promised that working harder would lead to individual advancement and to a more gender-equitable economy as a whole.

Except it didn’t. The eager young joiners of the “Lean In” circles watched as the number of women in leadership positions actually fell after the book’s publication, as the #MeToo movement exposed more intractable barriers to success and as Sandberg herself came under fire for her behaviour at Facebook.

It was all deflating, but really that deflation is just part of a larger trend.

A generation of millennials feels let down by our elders, experts, institutions or some combination of the three: those whom we were asked to look up to and trust in the most important arenas of life. Their supposedly sure-fire paths to success — or at least stability — now feel more like scams. We’re building up to a backlash.

Disappointment in the promises of mainstream politicians, for example, manifested in support for Bernie Sanders in 2016 and in the rapid rise this year of Alexandria Ocasio Cortez, the Democratic representative-elect in New York.

Her democratic socialist politics are a repudiation of what the establishment would have us accept. We’re hoping that she — one of us — will upend the system.

Further, our frustration with those who promised that politeness and order would bring about justice is revealing itself in a backlash against “civility” as such. We’re not willing to wait a decorous few days before castigating George H.W. Bush. We don’t feel guilty running Ted Cruz, the Texas senator, or White House press secretary Sarah Sanders out of a restaurant. Decorum may be nice, but the promises heaped upon it were lies.

“That s*** doesn’t work.”

Obama’s admission was more evidence that our disappointment and anger are justified. That it came from someone who had been in the position to hand down those same pronouncements made her acknowledgement even more valuable.

In comparison with the usual cant — that it’s somehow our fault that things didn’t turn out as they were promised, that we didn’t follow the rules closely enough — Obama’s frankness was a breath of fresh air.

Maybe it means the establishment is waking up, or maybe it’s just the former Flotus herself, whose clear view of reality has always been evident.

Amid our discontent, we’ll celebrate anything we can get.

• Christine Emba is an opinion columnist and editor for The Washington Post. Before coming to the Post in 2015, Christine was the Hilton Kramer Fellow in Criticism at the New Criterion and a deputy editor at the Economist Intelligence Unit