[stanfordkid]

Presumably the management at Dropbox has no reason to throw away money. He received this on a vesting agreement and has to hit goals to receive it.

He has run several multi-billion dollar units at Microsoft. Likely he had many other opportunities on the table.

Fact is it takes more than code to build something that lasts. You need to know code, understand people that write code, but there is a lot more to it than code. This guy was hired to multiply the efforts of hundreds of coders -- so all he had to do is improve each of them 5% to justify his salary.