Here's a link to a presentation that you might find interesting: "The Economics of Stock Photos". Much of the commentary is from Yuri Arcurs, the Godfather of stock photography and an inspiration for many of us who started submitting in early 2000. In my case, I began submitting in 2009.

https://youtu.be/SYvcRahmLZM?si=2r5D3TYWxW80ckDa