My point was that it's not fair that someone gets to pay a smaller tax rate just because his taxable base is larger. If anything, it should be the other way aro

My point was that it's not fair that someone gets to pay a smaller tax rate just because his taxable base is larger. If anything, it should be the other way around. My original income tax vs. capital gains tax parallel was wrong though, but the premise is the same. If Joe Schmoe has managed to invest $5K in the stock market and grew it to $10K, his capital gains tax rate shouldn't be higher than Zuck's.