World leaders who had chances to quit while they were ahead but kept going then lost everything?

[Lumine]

Napoleon could have indeed taken the win and go home so many times it's almost absurd, but it just wasn't in his character. Could have kept his throne - if not his Empire - as late as 1813-1814 too.

The Bohemian Corporal could have also stopped - he could have, he clearly wasn't ever going to - right after Münich and - outrageously - gotten away with a lot. I'd say March 1939 too, but I think that's were he was perceived to have crossed the line in the mind of the Appeasement side of the equation.

Charles XII of Sweden's hubris comes to mind, could have halted before the Russian adventure or even after the early part of it and kept the Swedish Empire going. Still, he didn't lose everything.

Mussolini obviously would have kept his power and newly built colonial empire had he had the sense to remain neutral in 1940. It's almost fascinating to think of the Fascist regime lasting long enough to find oil in Libya.

There are exceptions in the sense of those thrown into very hostile contexts... but you'll find far more examples of hubris leading to disaster. Generally speaking, there's no shortage of men who got very far by being risky all or nothing gamblers and kept at it until they ran out of luck.