SP500: tripled over 10 years i.e. ~12% a year. Reinvesting dividends gives ~14% a year
Meta: 8x over 10 years i.e. ~23% a year.
If growth was uniform over 10 years and compensation/savings was uniform over 10 years, total portfolio would be:
((1+r)^11-1)/r (geometric series since each year's contributions grow for different amount of times)
1 (this year) + (1+r) (previous year) + (1+r)^2 (previous-to-previous year) and so on
SP500: 14% -> $23M Meta: 23% -> $38M
Now, it's entirely possible, the compensation for a position like this runs into $10s of millions and one can easily account for non-uniform compensation.
Even in NYC, actually even in Manhattan, $10M is more than comfortable for retirement. It lets you draw $300-$400K (3-4% per year adjusted for inflation annually). If one is taking a short sabbatical, then it's a no-brainer.