Stadia is different, with this product Google is trying something really innovative. For one, the fact that Stadia actually costs money should be a signal of Google's long term ambition here. Yes, Fiber also cost money but was bogged down by the hell that is infrastructure development.
Stadia will require a substantial engineering effort from Google to make this work. The latency and network requirements are a great test to gauge network requirements as we move into 5g, AR, and self driving cars.
Gaming is huge and if Google can be the first to provide (viable) steaming as a service they can really threaten some of the incumbents like Twitch, Sony, Microsoft, etc.
Obviously Google doesn't have the best track record here but I'm excited to see them tackle this challenge.