There are a whole lot of dry cavers who take up diving (ok maybe its only 10 or 20 per year globally lol).
They rarely take anything like fundamentals and many actually don't take cave diving courses at all. The UK has a cave diving mentorship program, run by volunteers, and you can't even "sign up" for it. You need to be an experienced and savvy dry caver with multiple years of experience and club relationships to go down this path.
Yep, that jibes with my thinking that there are very few people in a position to safely go from non-diver to full cave in 150 dives.