Who is it that exactly made these rich people rich? I've never met a business owner who didn't do it him or herself! This idea they didn't build something because they didn't pay for roads is nuts. These are the people who are paying the highest taxes. Hence the actually do pay more than their fair share of those services.
Any mega rich family got rich and payed their taxes. Or they'd be charged. If they don't pay and they're not charged that's our governments fault. But after they pay taxes it's their money! If they want to GIVE it to their family or ANYONE else that's their right they earned it!
If said rich man dies with a billion dollars. He's been taxed at the highest LEGAL rate. That's all they have to do. After that there should be any taxes on that money. If it's used to make more money the profits WILL be taxes. Don't forget they also pay tax every time they spend their money as well. What is that makes people believe that money should be taxed if they decided to leave it to their family.
If you win lotto would you want you kids to set for life? Or should the government take it because your dead?