Quite a few billionaires (Buffet, Trump) would disagree with you.
I'm not sure what you're saying these billionaires disagree with. If you're saying that Buffet and Trump think estates should be taxed, I would point out that there is nothing preventing them from donating their fortunes to whatever cause they wish. If their will states that their money should be given to the state or federal government, that's up to them.
If I am a brilliant man and create a company (and create value), I deserve to keep that. But why should my descendants, who are by virtue of their birth part of a "lucky sperm club," entitled to all that wealth?
That doesn't sound like capitalism to me. Are you saying that at your death the company that you've started and built should be liquidated so that no one can benefit from your work after you're gone? In your opinion true capitalism means that no matter the amount of effort, luck, or work one puts into their life, the outcome should be the same?
True capitalism should require a level playing field when you start, and to really do that, when the final score is tallied, the slate should be wiped clean.
That's why such super high estate taxes exist. And typically they're not for you and me, it's for people over a certain threshold (say $1 mio + in assets)
I can't agree with you that that everyone with over $1million is super-rich.
Here's a very middle-class example: A 50 year old man with three kids under 18. He has $200k equity in his home, and has saved $800k towards retirement. He dies, suddenly. Is it the moral obligation of the government to force the sale of his home and liquidate his retirement account so that they can "wipe the slate clean" for his minor children?