Buying and Selling shouldn't be a taxable event until your money is off the exchange

Buying and Selling crypto shouldn't be a taxable gain or lose until the money is off the exchange. In the same way that printing a ticket from one casino slot machine isn't a taxable event either.

You are still in the casino (exchange) That ticket only had value because the casino says so. If an exchange halts withdraws, that $ amount you see is worthless. Why does it matter how much you had at one point when you could lose 50% just as easily as you gained it? Or in the event of a hack/scam/total exchange shutdown, you're left with $0

Retirement plans don't get taxed when you click the button to change your bond/stock ratio, or when you change investment accounting firms.