As a comment already says, this was due to meeting targets agreed 10 years ago.
Now a lot of that is due to share prices, and my opinion is share prices are not set by the market any more, are massively inflated to make the US government look good, but that doesn't have much to do with Cook, much like Tesla's share price doesn't have much to do with Elon Musk (I'm serious, the guy is good at marketing, but that only takes you so far).
There's been low interest rates for almost 2 decades now. One of the primary effects of that is inflated share prices.
So, to say the least, this is a complex situation. Comparing Cook's renumeration to a chinese worker is just silly.