Despite what you say, there is always risk for anyone involved - just because you say that you're not going to run off with everyone's funds doesn't mean you won't. Unless you have been vetted by a well known member here I'd doubt any information about you is actually you - much rather fake ID and the likes.
And no, IMO all ponzi's are scams for they are simply a nice way of stealing from someone else. Calling a sheep a cow doesn't make it not a sheep.
Yes you are right ponzi can be scam if the owner is a fraudster. Royal Casino is not looking to scam anyone, members of bitcointalk know me and one even lives near me (he hates ponzis btw:)) I am also known under different user here and no, it's not a shill account.