I've thought about this for a long time. If we wanted to actually tax this wealth, we should just make people pay capital gains on marked-to-market positions every 10 years. Now before everyone starts shouting "yea, but the valuations aren't value," you could easily tax them on the lowest reasonable marked-to-market nominal value over the last decade, and you'd still get that tax revenue, just a decade later. It's just a way to have a property tax on a very speculative type of property.
I've been a casual investor my entire life, and I still think it's ridiculous that you can just hold an asset forever and never pay a property tax on it, but some guy scraping together a life for his wife and kid has to pay property taxes on his house every year.