[zniturah]

Proof?

For winning any game at some point (at the end of the game) there will be a position with >99% winning chances. The move that follows are decisive.

[littlestymaar]

That's not how chess works. The move that follow aren't usually decisive unless you don't know how to play the game and make enormous mistakes.

Anyone that knows how to play can beat a GM with a big enough advantage at the end of the game (which is what's reflected in the win probability).