Americans with real wealth are holding long term assets such as land or a business. Warrens idea will cause these people to sell assets to pay the taxes or they will just pick up and leave the country. Unless the dims make that illegal. Either way it is a losing plan.
Besides with all the corruption in DC, many politicians will be subject to such a tax and won't allow it to pass into law to begin with.
There's something fundamentally unfair about having to pay your taxes legally and then have what you have leftover be subject to being taxed again and again by some greedy politician who doesn't understand human nature.
Wealthy people have influence and power. And maybe more importantly, flexibility in their lifestyles and choices in what to do with their money. They would never allow this to happen.