This kind of (ahem) "business model" has become rampant. We easily call out crypto scams, but the "buy now, I'll finish it whenever" strategy has been rotting away at the core of the internet since Kickstarter became a thing.
I mean, Tim McNamara's course is literally a scam. You paid full price (minus the coupon) for a product that was never delivered (and likely never will be), sold to you based on hype and Twitter clout. What the actual fuck? How many people were defrauded, but were just like "meh, what's a few hundred bucks?"
Well, like I mentioned in my other comment, I really liked his book Rust in Action so I signed up for his course, despite the price. But yeah, maybe it _is_ a scam at the end of the day.