a cusp - The top of something, like the highest point you can reach.

The top of something, like the highest point you can reach. Or what a narcissist says when they're about to crash and burn.

'He called it the cusp of his success, but it was all a lie.'

'She's on the cusp of greatness, or madness.'

'He said he was on the cusp of being a king. He's not.'