In corporate America, you always get support as long as things are going well. As soon as things go badly, people look for scapegoats.
I’ve had a manager before who supported everything I was doing but when he was let go, I was left hanging in the wind. I’ve slso had a manager who wouldn’t listen to me (I was the Dev lead), everything failed in just the way I warned it would and I could see he was going to blame me.
Never trust a company - and by extension your manager who represents the company to his reports.
In this specific case Mark Zuckerberg holds controlling amount of the stock.