Left means a gift via inheritance, which is the exact opposite of an estate tax (it's not a gift or via inheritance, it's a tax on the value of an estate and paid before distribution).
They aren’t entitled to their assets. They only have worth because of civilisation. How well do you think bill gates would survive in a mad max utopia that Randians fantasize about?
They could could have blown it on building a pyramid to house their corpse.
The government is not entitled to the assets.