I would be interested to see data on how much capital gains tax is paid by people in whichever (income) tax bracket, or how people's proportion of income tax vs capital gains tax lines up.

Savings interest and such is already taxed as income, no?

Hitting retirement accounts would make investing enough to retire harder, but tax brackets could be set so as to limit this effect (which, again, wouldn't happen) while still capturing an awful lot of real estate sale income. Almost any house in my city has gone up by enough to immediately put you in upper-middle-class range for your income by itself if you bought it even just a handful of years ago, so selling/trading/working in addition to that would tax the sale significantly.

I get that there would be a burden to "common folk" but I would really love to see how much, compared to closing the easy out for richer folk.