(I think these are correct)?...
DreamCast was the straw that broke the camel's back for developers when Sega dropped the DreamCast after a couple of years, like they did with their previous consoles.
The VirtualBoy destroyed the career of the GameBoy inventor at Nintendo.
Adam computer killed Coleco.
The popular Atari 2600 which gained great profits originally, bankrupted Atari after the '83 crash, which was mainly due to such bad 2600 titles being churned out in the first place - so it brought about its greatness, and own defeat.