Even if a "generator" miraculously produced a valid key (perhaps by stealing one from a legitimate bundle), using it is fraud.
You spend 20 minutes giving away personal data, signing up for recurring subscriptions you don't want, and you receive absolutely nothing. The "key" was a random string of letters that will return "Invalid Product Code" on Steam.
They rush to the Steam client, fingers trembling. They paste the code. They try again. The "story" of the generator is usually one of brute force
So, if it is mathematically impossible to generate valid keys, what are you actually downloading when you click that shiny "Generate Now" button?
You are then directed to complete a "survey" that asks for your cell phone number, email address, or credit card information. These surveys are . The scammer earns $2 to $15 every time you complete a survey, sign up for a streaming trial, or "verify" your age with a credit card.