Ton Roosendaal (Blender creator) estimated in 2018 interview that 3D software market is very small, and pulled up Autodesk's (3DsMax/Maya, etc) business results from that time, which amounted to 25000 - 30000 yearly licenses. He also claimed that Maya has "maybe 20" developers behind with things being similar for other products.
https://www.youtube.com/watch?v=qJEWOTZnFeg (jump to 1h mark)