To be fair it seems Nintendo came to realize that Sony was planning to use and discard them in the end. Nintendo simply bailed on them first to humiliated them as a strike back.
How? Sony was even not sure about putting Sony name on the PS. It was uncharted territory. Kutaragi basically have to fight arms and legs to make PS a reality.
Sony board was furious at the time when Nintendo ditched them and went to philips instead.
How Sony was planning to use nintendo and discard them in the end?