I know two different jurisdictions taxing a transaction isn't the same as double taxation, the important point was you already paid federal tax on the income and then large numbers of your transactions have further federal tax.

Now a capital gains tax of zero could theoretically be fine, except you haven't explained where the profit would ever be taxed or whether the remaining types of tax would bring enough revenue. Why should corporate profits realized into personal income be tax free? You're giving half an answer and asking me to take your word for it.

Once assets get well into the millions or billions most people won't actually spend more than a fraction of it on themselves, so sales and real estate taxes won't cover it. It could continue as investment money forever, I suppose, and if you say investment is always good for the country then that sounds good.

Except arguing private investment always does better for the country than government spending would be ludicrous. Fully privatized roads and bridges didn't work very well. Privately funded military would incredibly dangerous. We've had enough trouble so far allowing private contractors into actual war zones overseas; letting them use force domestically would be moronic. Private prisons have incentivized incarceration above all other solutions and where possible treated inmates like we treat factory farmed chickens. Public investment in higher education pays huge dividends in increased wage income taxes, and while we're stuck using loans so heavily the government profits somewhat on Stafford loans themselves, too.

Business needs publicly provided security and infrastructure just as much as consumers and wage earners. Technically a business needs those things before they can become a stable and profitable business. I don't see why encouraging investment and fighting capital flight require taxing corporate profits which relied on public investment at a rate of zero.

If you take home money on business or property based in the US you pay taxes on it which continue providing its security and utility. The only reason why capital gains shouldn't be taxed, that I've ever heard, is so people continue investing in the US instead of moving elsewhere...but who gives a shit if they move elsewhere? Let them go. There's always somewhere willing to tax less. They can move their business and/or their profits to fucking Somalia and pay zero taxes. A race to the bottom doesn't benefit us.