Using a pre-school level example
You have 10 apples. Dan has 4, so you sign a contract to give Dan 3 apples in exchange for a hug — because you’re kind. Now you both have 7, but 2 days later Dan goes on to sell his apples for $70,000.
Does he now owe you $30,000?
Were you wronged?
Or did you undervalue your product and give it away at a price you’re no longer happy with, now that it’s worth more?
Those apples could have equally become worthless, rotting apples.
This preschool-friendly example explains the ludicrous concept of renegotiating an active contract based on the success of the resulting product.
Risk is taken by the person actively procuring a sale. It could work, or it could not. As they’re staking their own apples, the resulting profit is nothing to do with you. Just as a resulting loss isn’t your responsibility either.
The person taking the risk of a failed sale is the person owed the reward for a successful one.