You also need to consider that the median tenure at these type of companies are 2-3yrs[0][1][2] (1.1 at google!). In my experience that's not enough to get the full stock grants.
So even from those that could make it very few stay long enough to make these great riches your imagining.
Google and I believe Facebook have uniform monthly vesting, so these figures are accurate for any amount of tenure.
TC is not computed using the total value of your grants, it’s based on the amount that will vest over the course of a year. Yes, that means there are engineers getting grants of $2m+ over four years (putting TC around $700k+)
The average tenure is short not because people are getting fired for underperforming. It is short because 1) a lot of people get hired with massive YoY growth even for their size, and 2) people leave to earn even more at other companies in which case they’re still getting the compensations discussed here.
I'm not imagining these numbers - I've seen offers from Google and I also know what I make (as well as what many of my peers make). Standard procedure is for vesting to start pro-rata after 1 year, so even the short-term Googlers you mention would hit their $500k+ annual targets. As another commenter pointed out, I am talking about annual stock, not total.
TC is not computed using the total value of your grants, it’s based on the amount that will vest over the course of a year. Yes, that means there are engineers getting grants of $2m+ over four years (putting TC around $700k+)