Nobody tells a person at the height of their career that they are wrong. That is not a compliment. It is a warning sign.
A real diagnosis, not just a proverb
In 2009, physician and former UK Foreign Secretary David Owen and psychiatrist Jonathan Davidson published research in the journal Brain describing what they called hubris syndrome, a pattern observed in leaders who had held significant power for an extended period. Its features included growing contempt for advice, restlessness with the details of a problem, and a diminishing circle of people willing to disagree. The condition was not caused by a single decision. It was caused by the slow disappearance of the feedback that would have corrected it earlier.
Why the fall looks sudden but rarely is
The person at the center of a public downfall almost always describes it as unexpected. The people around them almost never do. What changes as someone accumulates authority is not their judgment on day one. It is who still feels safe enough to tell them when the judgment is wrong, and how much of that feedback actually reaches them before a decision is made rather than after.
Where to start
The safeguard is not humility as a personality trait, it is a maintained habit of asking a specific person, regularly, for the version of events they would only say if asked directly.
If you cannot name who currently does that for you, that absence is the actual risk, not any single decision you might be about to make.
Reading whether the people around you are genuinely being candid, versus telling you what they think you want to hear, is a judgment that gets harder the more senior you become, not easier. What this gives you is the specific habit worth checking for, since the symptom is silence, not conflict.
There is a specific way to ask for the version of events someone would only say if pressed, without it feeling like an interrogation, and it is worth setting up before you actually need it.