If a user knowingly choses to install a plugin that includes Sambreel, it's not a scam. It's their browser to do with what they will. Having said that, I'm guessing that there are a lot of scummy plugins/extensions that don't alert the user to Sambreel being installed. That's what's the scam here.

Also, the target of the funding shouldn't enter into a discussion about legality/ethics of the method.