$20k? I thought there were millions of USD on the site. I'm not a whale or something, but I had around $400 on the site. My balance was $150 and I would never deposit more but my friend offered to sponsor my poker game and I deposited $250 more just couple of days before the site disappeared. Was I among those few unlucky ones who had much more than $100 on their balance? Too bad.
It's possibly around the 20K range for the exit scam, but it could have been a little more if they were selectively scamming all along. If the amount was in millions of USD, we would have seen a lot of noise on sites like reddit, trustpilot, casinoguru, askgamblers and this forum.
For a website that was already struggling, I would say it's just the unlucky few that got struck by the exit scam.