system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5 How did the owners of Grumpy Cat turn that whole thing into a money making enterprise?

I've heard they quit their day jobs and are raking in millions. What exactly are they selling and who is paying them?
gpt
The cat, Tartarsauce, has numerous books, meme's and even a movie created around the idea of 'Grumpy Cat'.

Since the cat cannot legally have money in an account under her name, the owners of the cat are the ones who benefit. (Like any animals in a movie, but this sense is more extreme)

They get paid from royalties of all the books, pictures, calendars, toys, cothes, posters, games movies and other things.