If you earn an income selling goods or working for a wage , and you earn more than a certain threshhold you will owe income tax on those earnings.
If you spend all of the remainder you will never owe any capitol gains tax.
But if you buy land , or stock in a company or otherwise invest in securitys you might, when you sell again, owe a tax on its increase in value.
So you pay a tax on your money , and if you invest well you will be taxed again on the same again.
Increasing the capitol gains tax will reduce investment , make it harder to buy and to sell farms and homes and decrease the ability of 401k type retirement accounts to carry their retireees thru retirement.
Eliminating the capitol gains tax will still allow the government to tax all earnings once , and if investment and sale of major propertys and securitys is easyer to make profit on , it would promothe business and employment.
You can call a tax on taxed money "fair" if you really have to think in this peculiar way, but it is the sort of fairness that promotes starvation being shared rather than prosperity being unequally distributed.
Yes Warren Buffet is kidding , I can't beleive he doesn't understand this stuff.