Then simply don't tax fixed assets. Sure, sure, then people will simply avoid taxes by converting cash and other assets into properties that are not directly taxable, but that's just how these cat-and-mouse games go.
That's what you should be doing because the government should be extracting taxes on the exchange of fiat for for assets and then back to fiat. That's how things already work in fact. People are just angry that other people find value in e.g. Elon Musk and Jeff Bezos when they otherwise don't and want to tax away their entire existence because justice. The alleged problem is those people still have billions even after paying taxes on the acquisition of assets. I'm all for fixing tax loopholes so people can't hide money and avoid existing taxes. How about starting there and actually taxing the tangible before trying to tax the intangible? Companies can and in fact are supposed to grow in value. If the company you own becomes super valuable, you win. If we are unhappy how valuable some companies can become, then you need to cap that and actually break the companies up or progressively more heavily tax profits (which are tangible) such that the company can only become so valuable to investors/owners after which it ceases to provide any additional value because it makes too much money. But since everyone hates Bezos while happily paying for their yearly prime membership, that won't happen. And indeed, Amazon doesn't make incredible amounts of money, it's just ubiquitous and provides a lot of utility which is what makes it valuable. Bezos fought investors for years and years pushing his narrative and strategy of minimizing short term profits to build a company that people literally can't live without and it worked. Crazy. Maybe the government should just buy Amazon...