Income tax is only applied to taxable wages
, not capital gains
Of course, whatever miniscule (in comparison to the capgains) amount of taxable wages they have they'll pay income tax on, but not the capgains.
This is why, for example, Steve Jobs took $1 salary a year. So he could completely avoid income tax. Most aren't that extreme, but the vast bulk of the upper 15 earnings is in capgains.