I think it will take time and community demand before Rollbit reconsiders to open up sports betting. It's not that impossible for them to get onto that track and I think they can pull it off but Rollbit was likely want to be unique in its own way but getting onto sports betting as a huge industry and more opportunities.
I believe that nearly everyone starts a sportsbook eventually, it is like the "thing" that you do when you grow big enough. I have worked with casinos before, in marketing usually but I know how things are done and we all had the same chat app that all workers chatted and we knew what was going on.
The most important thing is to get the customers, we all know that and that is why marketing was the hardest department because we required every single cent to spend on marketing to grow, however the moment you reach to 1000+ daily gamblers, making a sportsbook is a profitable thing, you do not really pay it neither, it is nearly zero risk, all you have to do is find a provider and you basically become an affiliate to them and people play on your website but really they are playing on your provider, you are just the middleman who take the money and give it to the provider, and you take an affiliate cut. However, that is still insanely profitable if you could get like 100+ people to bet on your website, hence why everyone does it.