> Taxes on capital gains are morally right, but wait until the gain has been realised before levying the tax.

I tend towards your morality, but I would rather argue from a practical perspective.

My proposal is that we should levy tax on wealth when we can actually measure it. "Market capitalization" is largely illusory, but public stock markets make the per-share value real. As for private equity… well, it would be inappropriate to take some investor's implied valuation for granted, but neither should we allow multi-millionaires to hide all their wealth in a do-nothing corporation registered for a few hundred dollars and then claim to have no liquidity.

All this stuff about "resetting cost basis" encourages playing games, and those with the most resources will be best at dodging the taxes (the more complex the rules, the more so). My perspective on this is perhaps informed by living in Canada, where capital gains are grossed down rather than having the American distinction between "short-term" and "long-term" capital gains and complex rules about "wash sales" etc.