I like to think of it as something similar to watching a football match from the other side of the fence. People who paid the ticket, are loyal fans. People who didn’t pay, but still want to see the match, probably aren’t even part of the target audience. Some of them might be, but that’s a small number.
So, when the football company says that they’ve lost the sales of x number of tickets, they are actually saying that if those people had enough money and if they cared enough, they might have paid this amount of money.