The use of death "wills" is a major problem in the modern world.

In the past, only a very few people/families lived like royalty. Today, thousands of people/families do.

What this does is create thousands of people passing on massive wealth to offspring who never learn to contribute anything to society. To them, living a royal lifestyle is normal and expected for them, their children, and their grandchildren. That money basically just sits in banks and gets moved around for centuries but never contributes anything to the welfare of the country that generated it. Such a system will collapse over time.

A forced spending/donation/tax of 90% of everyones wealth at death is more in line with the modern world. They can keep that money in their families but it must be spent, put to work, in the country by buying things. It cannot just sit in banks so that extended families get to live like royalty forever.