[QuantumGravy]

That's a perfect illustration of what I'm getting at. You can just keep redefining whatever 10x means to make your point. In your example, minus the the initial "Haha", this might as well be lifted from a cover letter or a consultant's sales pitch:

"I have a highly unique track record of delivering entire projects that would take longer schedules or larger teams to complete. Clients have called me a force of nature, a prolific creator that delivers when the job must get done and one who lifts up entire teams to be better when they work beside me. I provide the right kind of compounding experience that goes a long way."

Such confidence. The hiring managers are swooning over here.

But that's beside the point. Where's the study that meaningfully quantified that type of performance? Especially at an individual, repeatable level? If we can't answer those questions, I must conclude that the current usage of 10x developer is about as meaningful as "passionate ninja rockstar".