I think a law stating you can’t borrow against unrealized gains would be sensible.

You can keep your unrealized gains forever, live of your dividends for all i care, and pay no tax. But realizing them, either through selling or borrowing against, triggers a taxation.

Aren’t dividends taxed?

Dividends paid out to taxable accounts are taxed.

Dividends that pay into non-taxable accounts can accumulate until they are withdrawn.

So, for instance, if you own $100 of Exxon in a regular brokerage account and $100 in an IRA, the $5 dividend you get from the first account is taxable but the $5 from the second is not.

This gets us to the idea of Trusts, Hedge Funds, and other tax-deferred vehicles. If you give $100 to a Hedge fund and it buys a stock in the fund that pays dividends, it never pays you the dividend on the stock so you never have to realize the dividend gain. You simply own “$100 worth of Citadel Investments” which becomes “$105 worth of Citadel Investments” when the dividend arrives.

I think dividends in a tax-exempt accounts, like a traditional IRA, are only not taxed if you reinvest the dividend or just leave it in your brokerage account. If you move money from your IRA account to, say, your checking account, that’s when you pay taxes (and there are generally fees for moving money out of tax exempt accounts without meeting certain conditions, like being of retirement age).

I think dividends in a tax-exempt accounts, like a traditional IRA, are only not taxed if you reinvest the dividend or just leave it in your brokerage account.

Right. Although, with a ROTH IRA, you pay taxes before you put the money in. Then you earn tax free even after you take it out. That makes it the preferable vehicle for long-term savings (you should expect your initial investment to double every 10 years, assuming a 7% ROI which is fairly modest - so over 30-40 years you’re saving 8x on the eventual withdrawal).

But this isn’t just limited to IRAs. Using investment funds, you can pull the same trick. Buy the fund, then allow the broker to shuffle the investments within the fund as they please. You only “earn” the money when you exit the fund, in the same way you only “earn” your retirement when you withdraw from your IRA.

Savings accounts and trusts can then be structured to be inheritable tax-free, with your heirs having access to withdraw from the fund without ever actually owning the money (and thus needing to pay taxes on the inheritance). And to make it even more squirrelly, you can borrow against these funds, which allows you to make large purchases without ever actually spending any money. This maneuver, plus a cagey use of declared loses, means you can avoid paying any tax on any investment income virtually indefinitely.