I don't have numbers on that but I bet purchase of brand new MacOS compatible devices is 99% or more from people who already have at least one or more other Apple devices.

Sure they are probably thousands if not millions of (in the positive sense) nerds and geeks posting on HN about buying a Mac first hand, not second hand, solely to put Linux on it but even then would be a drop in the ocean compared to the remained sales.

Still if you have numbers on that I'd love to be wrong about it.