What's weird about this "curse" is that all four companies were at the time coming off a period of immense success; the PS2, Megadrive, and 360 were the most successful systems from each manufacturer, and while the SNES was not as it faced stiff competition, it eventually emerged victorious and reasserted Nintendo's dominance over the console market.
Then, collectively, they all lost their minds and shot themselves in the foot.
It could be argued that it was precisely their success that lead to overconfidence and subsequently grave mistakes. Pride cometh before the fall, as they say.