I agree with you, this is turning into a serious problem.

It's one thing to have a free and open platform here, but with this much identity theft already there needs to be some sort of framework set in place here to prevent people from literally defrauding honest users and walking away with massive amounts of cash from plagiarized content.

There are plenty of plagiarism checkers that exist online - CopyScape is one, and Grammarly I believe has that functionality as well - which might be something to consider integrating into posting. Barring that, maybe limit new members' ability to post/comment/upvote until they verify their identity?

The former seems like it would be an expensive, logistical nightmare, while the latter would have too much of a chilling effect on new membership.

Cheetah and bots like it are a great idea, but there's only so much they - and their developers - can do without the support of the community. I'm talking full support here, actively looking for and rooting out plagiarism whenever you see it - especially when it comes to identity theft. There's too much at risk, and too much to potentially lose, to not be hypervigilant.