I don't think there is anything more to it than self preservation. All humans and I'd say living beings are good at it.

This is why martyrs are so praised. You have to overcome this instinct of self preservation to give up your life. I suspect most people can't do it in the heat of the moment.

Basically what others have said, it doesn't matter if Jensen is good at his job or even if nVidia prospers under Jensen. I don't think the board members care one lick about that. What matters to them is their own self interest and it takes a lot of experience to realize that executive leadership and even the board does not instinctively value the goals of the organization above their own self interest. I submit this is true because of the massive amount of bribing err I mean incentive alignment that the organization gives in terms of like stock options or bonuses for meeting certain targets.