If you invest in S&P 500 index fund you don't need to sell until after retirement.
But a material chunk of the $14M belongs to the government (not available for the individual to spend).
If someone takes out a $2M loan at the age of 58, and retires at 59 (before any of it is paid back), do you think that should be money considered in a retirement calculation?
Also, Capital gains is treated differently than ordinary income.
Your income tax bracket is irrelevant in determining your capital gains rate (at least for now).
Income tax bracket doesn't directly correspond with capital gains brackets, but total income affects the capital gains tax rate.