A lot of it has to do with the government regulating people's actions. Its mostly artificial so I doubt that it will stay as a long-time trend. Things will slowly but surely go back to how they were, so online gambling casinos as well as physical casinos should see this as a short setback. I think they would have been better prepared if the governments gave a few months warning before implementing further restrictions and lockdowns. Most people had no idea what the government was going to do next and it really messed up people's businesses.
But there's nothing that the government can do if emergency needs to be imposed in terms of limiting people from attending wide gathering like sports events. They are more on preventing the spread. I understand what you are trying to point here and I agree it's a messed with every business when the government didn't give enough time before implementing rules and gambling is included to several rules that are applied.