Jack already gave 15 million shares which represented 20% of his own equity back to the option pool and to a foundation to help underserved communities, and he's committed to giving an additional 40 million shares to the foundation..
He's going to give away ~75% of his ownership in the company he founded to employees and entrepreneurs in underserved communities. Whatever the price is on IPO day, this will surely amount to him giving away at least a billion dollars.
I can't fathom why people are so cynical, this is amazing.
Envy, greed, and or the general dislike of seeing other people succeed is almost always the explanation. That's why the same reaction happens over and over again, regardless of who it is that is getting rich. It's common believed that to get rich, you must take that wealth away from someone else (or otherwise do something dastardly); the limited pie of wealth fallacy.
How do you make something valuable? Convince others it has value, and do it with only 20% of your stake.