Actually, I'd say there are NO people who literally worship the Christian Satan. There are in modern days atheists who basically troll with that idea, but that's about it. The proposition that some people KNOW that Christianity is true, Satan will just get them burned for eternity, but, meh, just want to spite God and burn for ever, was and is just an intellectual cop-out. It really makes no sense whatsoever.
It's the rationalization the intellectually challenged reach for, when they have no good arguments to convert you to their flavour of fanboyism. Of course they know they're right, so why don't you see things their way? Right, you must be a shill for the other camp. It's really no different from Mac/Linux/Windows fanboys postulating you're some Microsoft/Apple/IBM/whatever shill if you dare as much have an open mind about the opposite camp. They "know" they're right, and if you don't see things the same way, you're just lying for some ulterior motive. Christians did the same.
And we can know they were wrong about other groups, about which the same satan worship or intention to spite god or harm the true faith or whatever, was postulated. E.g., it was popular to say the same "they're just trying to spite God" about Jews. We're pretty sure that those guys didn't. E.g., about pagans. No, they were just worshipping their own gods, for purposes like fertility or protection, not to supposedly spite the one they knew to be the one true god. E.g., about the templars. Yeah, we're pretty sure that not only those guys didn't worship a demon called Baphomet, but nobody had even heard of Baphomet before. Etc.
And that the rituals postulated, again, make no sense for any of those. E.g., pagan cults didn't involve reciting the Lord's Prayer backwards, or anything.
So, you know, even by simple induction, why would I believe that it would be more based on reality for any other group?