What you buy: Workshop prompts on card. But we don't purchase things just for their function. So what is the real reason people buy?

What you buy: Workshop prompts on card. But we don't purchase things just for their function. So what is the real reason people buy?
On the Workshop Tactics website, you’ll find 56 free product team workshop exercises. However, they aren’t unique. You’ll find them scattered around the internet and in various books. So if they are free, why do people buy the £89.99 card deck?