You're absolutely right if the discussion was about the business success of the game console, but it's not. It's about Microsoft always having 'hardware that's killing it', which is made pretty untrue by the consoles' faulty reliability in the past.

A whole cottage industry of aftermarket console cooling apparatus was spawned due to the first Xbox's history, and it didn't help whatsoever in staying the problems that the second one had.

It was a business success regardless, but that's not the topic at hand.