Casinos in the CT, and AC aren't doing well because they didn't (and still don't) respond to the demands of the market. People don't want boxes of slots and tables. Go to one of the many successful casinos in Las Vegas and you'll realize very quickly why Foxwoods and Mohegan are tanking. The two here overexpanded their gaming space, instead of adding in attractions and amenities that make them destinations that people will travel to from far and wide. The vast majority of properties in Las Vegas, especially the ones that are most profitable, earn the majority of their money from non-casino revenue - restaurants, shows, retail, exhibits, nightlife, other attractions. The ones here have tried to do that, but responded too late and with very underwhelming options.
A box of slots in East Hartford is not a meaningful long-term revenue producer on any scale. No one wants to go to East Hartford, just as no one wants to go to Ledyard or Uncasville. Not to mention, MGM is going in half an hour north, and Wynn is going in 90 minutes northeast. Both of those properties will collectively crush CT casinos. That's why Mohegan and their cronies in Revere who lost the bid for Boston's gambling license are pulling Stop lawsuits out of their ass to try and stop Wynn. They know they screwed up royally in the 2000s and are paying dearly for it now.