Of course being a unique gambling casino would be better than a copycat, no doubt about that, but in reality it's practically impossible. The established model of sports betting, for example, is so good, so convenient for bettors, that with making something entirely new you are risking to be left without customers. Let alone slots that are rented from software providers. They are all the same. How can you be unique in that department? Yes, some gambling sites have their own slots, but it's only one or two among many hundreds of leased ones, and that’s because it is very costly to create a good slot.
That's why I think it is enough to be a bit different, in a good way, to win the competition these days.
True, it will require a huge upfront investment to try to differentiate from the other casinos
without any guarantee that this will bring any clients, Exactly. Why people should go to your platform if they are already using several gambling platforms and absolutely satisfied with the experience? When there are so many good online casinos there's a high probability that your site will be worse than others if you are trying to create something new. I'm not advocating copycatting here. Please, do add some features that no one else has, but only if they are really useful. Don't make otherness your main goal.