Because when you die it is no longer your wealth. You do not have any "wealth". You do not have anything at all, not even your own body, there is no "you" anymore. You're completely gone, nothing left, nada. So you will not be "paying taxes on it again". A dead person cannot be forced to pay tax. They're dead. Get it? Nor can they be "punished for being successful", or punished for anything at all. So your mistake is thinking that it belongs to you. When you die it certainly does not.
Instead of trying to leave your heirs a bunch of money they did not work for, they'd all be a lot better off if you leave them strong, fair and free country they can be proud to live in. Without excessive national debt. Where anyone who has the desire and the ability to get higher education can get it without going into lifelong debt. Where they don't have to worry every day for their whole adult life if they'll be able to get health care for themselves and their children. Where anyone who wants to invest money or start a business can do it without worrying that the game is rigged in favor of those who already have massive amounts of money. Where basic needs of all children are met so they don't end up thinking they have no choice but to take what they need and turn to life of crime and make the streets unsafe for all. Where the average person is not afraid to invest in a home mortgage for 30 years because unregulated investment bankers have turned the housing market into a Ponzi scheme.
A country where you are respected for who you are, and not for what you have.
And those things will only happen with well funded government and never if a few rich people keep owning the country.
If you truly believe in capitalism you should be very happy to support my proposal because it will allow everyone to keep more of what they have earned with reduced income, property, sales and corporate taxes.
See the beauty of this? You get to keep what you make for your entire life. And no one gets what they don't earn.
Everyone starts out with a fair chance to compete and the government is well funded to provide safety and support that allows everyone to reach for success.
It is the epitome of capitalism. And fairness. I invite you to climb aboard.