That's why long-lived organizations have internal checks and balances. Even if the individuals eventually fail sometimes, the organization can identify and self-correct.
Checks and balances are for preventing individuals' interests from swaying the organization. They're useless when the whole organization's interest, or even survival, is at stake.
Mozilla is almost completely dependent on its partnership with Google, and apparently, the majority of Mozilla's board members are okay with this. And of course this decision has everything to do with the fact that 90%+ of the organization's revenue would evaporate if they refused the partnership.
Instead of debating theoretical scenarios, wouldn't you like to describe what such a situation would look like so we could reason what layers of internal or external controls would have to kick in so the issue could be corrected?
But one doesn't need to care a lot about money in order for money to become a major factor, perhaps unconsciously, in your long-term decision-making. I remember there being public anxiety whenever there was doubt about whether Google would renew the search deal. Over time, that kind of anxiety takes a toll. Perhaps it's less of a concern for ordinary employees, but top-level executives definitely think about money a lot. $300M/yr is a lot of money to take for granted.