From a quick scan of the article, it seems to me that this person was in the upper echelon of FB engineers, leading very successful teams working on important FB products. Considering the staggering success of FB as a company (and as a stock) over the past decade, it doesn't surprise me that a top engineer would be making serious bank through stock options/grants and a gold-plated, Silicon Valley salary.
But I don't think there's much of a story here. IMHO, it seems reasonable to expect a top-level contributor to a hugely successful, immensely profitable company to be extremely well compensated. I'm sure there are similar stories about thousands upon thousands of other superstar engineers from companies like Microsoft, Google, Amazon, Netflix, Apple, etc., going back many years/decades. Sure, it seems these folks have been blessed with an excess of good fortune compared to others... but that's how the world works. Some will strike it rich, through hard work, good luck, good genes, and other factors, but most won't.
I think of myself as an example on the "good luck, good genes, hard work" side of the equation, albeit at a much more modest scale. I got lucky to join a small, dot-com era startup in the late 90s, and got lucky again when our little company was gobbled up in a series of acquisitions. This eventually led to some stock options/grants and, eventually, a nice base salary with very nice yearly bonuses that I was savvy enough to invest wisely and keep earning/receiving for many years. But rather than telling myself that I truly "deserved" all that, I honestly feel like I just got lucky to be at the right place at the right time and with the right skill-set to take advantage. Very similar to the FB engineer who wrote the article, except he got even luckier to be hired at the right time by one of the most successful companies in the world and to make certain moves in his career that vaulted him up the ranks. It's not all that different from someone winning the lottery or receiving a big inheritance. Luck—both good and bad—is quite random and capricious.