To be fair, from stripe's point of view, how would they know that you and the alleged customer are not in on it for some reason they don't know?

"Friendly fraud" is when the cardholder is in on it. They or an accomplice they've given access to their credit card go to a merchant, order and receive an expensive item with the card and then file a chargeback claiming they didn't make the purchase so they can keep both the item and the money.

What would be there to gain? The merchant loses money to the credit card processing fees, chargeback fees, and shipping cost along with the loss of the product, they gain nothing. Its a pretty expensive way to send a customer a free thing.

? in on what?