The main difference between 5e and all the others, AFAICT, is that all the rest of them, no matter how high they started, plummeted around year four (give or take) and then trickled until their ultimate end. 5e was still RAISING by 2018. This is why it's totals, no matter how much the market may have been smaller at the start (I don't know about that, but I believe it was smaller than the initial market for 1e, at least) it just keeps on going and going.
I know that as a retailer, in 2e, 3.5, and 4e, by this time, I was lucky to turn over a single copy of any of the core books in a month. New splat books would sometimes only turn over one or two copies in their lifetime. 5e still sells dozens (or more) of every book released, and we still sell core books multiple times a week! AND that's with all the other ways of getting the books competing with us (which never used to be quite the case!)