Those are all pretty bad, but I've gotta say Sega Saturn. The Saturn is what really drove Sega out of the console market. (The damage had already been done by the time the Dreamcast released.) A lot of the Saturn's missteps had to do with hubris from Sega of Japan too. Sega of America wanted to keep supporting the Genesis, but Japan wanted to kill it off quicker, because Genesis/Mega Drive was a lot more successful in the US than Japan. Of course, the also botched the launch of the Saturn in the US and the library was not nearly as good as the Genesis library.
It's the console that drove a console maker to become 3rd party. What a disaster.
curl-6 bet me that PS5 + X|S sales would reach 56m before year end 2023 and he was right.
My Bet With curl-6
My Threads:
Master Thread, Game of the Year/Decade
Switch Will Be #1 All Time
Zelda Will Outsell Mario (Achieved)
How Much Will MH Rise sell?
My Bet With Metallox