Here is a very simple analogy.
If you had the foresight and funds to buy 3.9M shares of Ford stock when it was $1.50, and you sold those shares last week for $14.50 - how much did you make?
$50.7M. Would anyone here (including Mark) say that was too much profit? Of course not because it was based on an increase in stock price.
That's EXACTLY what happened here. No more, no less. This was not a simple bonus check. I don't know the mechanics of the deal but Ford could have simply bought $3.9M shares at $1.50 and sold them last week, making Ford's cost more like $6M 2 years ago.