I bet there were similar reservations about the initial iPhone, too. CapEx spending to develop the Vision Pro will probably be spread out over years, in which Apple will undoubtedly release the Vision Pro 2, 3 etc..
I'm not an accountant or an R&D guy but the first version always costs the most, right? Improvements over the years cost less and less as the platform is more established, I would think (if all other costs remain relatively stable).