Flappy Bird
The rise and fall of Flappy Bird was a doozy. This was a popular app that became extremely competitive among teenagers and young adults. It was almost as crazy as Angry Birds, and probably would have reached that level of fame before the developer took it off the market because people were getting too "addicted" to it, as the creator has said. Only ancient artifacts, such as an iPhone 5, would have something like this on it...
MoviePass
This was a deal that seemed too good to be true -- because it really should have been. MoviePass offered its customers to see one movie a day for the price of $9.99 per month. This was a totally unsustainable business model and it crashed and burned pretty quickly. It officially shut down in September of 2019. It did inspire Regal and AMC to create their own membership deals, though. They're not as good a MoviePass, but it's something!