My point is that there is a much larger audience outside of our own "niche". The fact that we see a lot of developers with Macs, does not mean that they are a large audience among all of the Mac users.
My brother works at an Apple shop, and the vast majority of people he has to attend come from all walks of life, they are not developers/enthusiasts.
There are around 20 million developers globally and Apple has been selling 4.5 million Macs per year on average since 2013 (most of them MacBooks).
If 27% of all developers are using Macs (as the stackoverflow survey indicates) and the machines are replaced after 4.5 years then developers would be buying ~1.2 million Macs per year, 27% of all Macs sold.
In terms of revenue developers are probably an even larger share, perhaps a third? That's still not the majority, but it's certainly very significant even assuming that Mac users are overrepresented in the stackoverflow survey.
We are talking specifically about Macbooks. Among buyers of the iPhone, iPad, and iMac is a broad, society-representing demographic. For Apple laptop it is overwhelmingly developers and aficionados (e.g. designers). I don't have any official stats, but I don't know a single person who owns a Mac laptop who isn't in those two categories.
My brother works at an Apple shop, and the vast majority of people he has to attend come from all walks of life, they are not developers/enthusiasts.