I think it's a simple as ALL forums have lost numbers in members.
Much probably had to do with the difficulties of moving money back & forth.
As a matter of fact I would just about guarantee that has more to do with decreased numbers than forums being a thing of the past.
As I mentioned, I believed sports betting legalization would change that & some of the millions of new bettors would find these sites.
But all of that is on hold now.
We will see though what happens