Cloning toppers in the industry is not something invented by crypto gambling sites. Just look at the several examples that Google is giving us:
Not all those that copy others are dying out, as you can see from the list above. If you are honest with your customers and the functionality of your site is on the high level, you have every chance of being successful, but being at least slightly different wouldn't hurt, of course.
Obviously you do not have to reinvent the wheel to get rich, you could copy what someone else does and become rich as well. As we all know the story of facebook, they had myspace way way way before facebook came out, but myspace was sold for 500 million or so, whereas facebook is now worth 100+ billion dollars along with whatsapp and instagram calculated in it (now called meta).Not all those that copy others are dying out, as you can see from the list above. If you are honest with your customers and the functionality of your site is on the high level, you have every chance of being successful, but being at least slightly different wouldn't hurt, of course.
So, we could easily say that if there is something out there, and you do a better version of it, then you should be getting rich too. But remember that these people are doing it and have millions of dollars, so you need to do something much much better, and can't do that with just a few grand and hiring a developer.