The reality is all the money they make off Linux is with workstations cards or HPC. Neither of those market niches are likely demanding Wayland support since stability is a hard requirement and Wayland really isn't sufficiently mature yet (nor does it really have sufficient market adoption).
They're a business, so when their customers need it, they'll support it. Until then, only hobbyists or an insufficient part of their customer base is interested, so understandably, they're not investing in it.
They're a business, so when their customers need it, they'll support it. Until then, only hobbyists or an insufficient part of their customer base is interested, so understandably, they're not investing in it.