Whether it is a big company or small company, or it's a brand/non-branded stuff, everything in this world needs marketing. I think it is not a biggie with a casino like Roobet or any other one. As of now, Roobet is a big brand in the casino category, they may leave the marketing as it is and they will still survive the worst storm of competition. However, let us not exaggerate things here because at some point others will take over the ground, peeps start liking new ventures, this makes the previous ones fade away from the memory.
Now just to keep that memory fresh we need that continuous ticking of the brand name, its images, and videos circulating everywhere. I am sure that's the only way to keep everything encircling for a business.
Roobet is doing the same and they are doing it perfectly.
Online gambling is a hard business to be in as daily new casinos are popping up and some try to offer new features/games/giveaways that can't be found on other sites. So it is one thing to keep attracting new costumers but the hardest part is making sure the people return to the site and keep playing. As you say, Roobet is a pretty big name already and they keep doing stuff (like the art contests) to stay relevant so that is nice.