That assumes he held his stock. Everyone I know seems to sell as soon as it vests. If so he didn't get all the return you quoted.
There are so many ultra-optimistic assumptions in that post it’s hard to pick out just one. If all of those numbers were true it would represent the career/salary growth of an outlier employee. Although I’m sure it does happen every so often, no way the median “rank and file” software engineer at any of these top companies has that kind of outcome.
Facebook stock was ~$25 in June 2013 which means he has got 10000 RSUs of Facebook while joining. Value of this stock today is around $1.5M. He is in Seattle and his taxes are way low compared to CA.
OP must have been scoring refreshers ($40k (Jan 2014), $100k(Jan 2015), $150k(Jan 2016). Let's assume has around $300K of vested stocks.
OP has made $1.8M in stocks at Facebook and may be some good bonuses and quitting Facebook after has vested his initial grant.
You shouldn't quit Top Tier tech jobs period unless you're this author who has made >2M.
At the growing pace of FB, Google and Amzn, anyone quitting at L5 levels will learn that they could have ended up as Director in 6-8 years if they work hard in these firms.