You could tell the same story about a rising sports team replacing their star coach, or a military sacking a general the day after he marched through the streets to fanfare after winning a battle.
Even without the money involved, a sudden change in leadership with no explanation, followed only by increasing uncertainty and cloudy communication, is not going to go well for those who are backing you.
Even in the most altruistic version of OpenAI's goals I'm fairly sure they need employees and funding to pay those employees and do the research.