That's pretty intentional. A venue really doesn't care how many people go, they care that the show gets "sold out".

A couple of my friends are scalpers. They said there's a limit of 8 tickets for most shows per address, but if you walk in with thousands of dollars in cash that limit goes away. Online it's a little different since you need to put your address in for your credit card, but there's plenty of ways to get multiple addresses with your name for credit cards.

They make more than me as a software engineer, but they can easily lose thousands if a show doesn't pan out. They follow tours across the US and hope they find "the one" that makes them rich.