Ad-free Chambers! A good example of why people demand a service for free and will pay good money for it. People are willing to pay for a service only if they believe they can get it for free first.

So... demand curves slope downwards. People are willing to pay for a service only if they believe they can get it for free first. A perfect example of this is a paid subscription for ad-free Chambers, which most people won't bother with because they just don't care, but some people will because they *are* willing to pay for a service, but only if the price is just right or just for convenience.