It also ignores that redistribution results in less "private good" (GDP) for everyone, because by definition it's taking wealth from people who on average have demonstrated more ability to grow wealth and giving it to people who have demonstrated less ability to grow wealth. Imagine two otherwise identical people, one who's capable of generating 5% returns on his wealth and the other who's capable of generating 2% returns. If they both start with the same endowment, after 100 years the total amount of wealth they've generated will be much greater if they're allowed to keep their own wealth than if the 5% guy's is continuously redistributed to the 2% guy (because every dollar redistributed will earn only 2% return instead of 5%, meaning it's been used to produce less value for society).
More practical example: imagine if after Paypal, Elon Musk's entire wealth had been redistributed to all Americans. Assume generously he had 50 billion (pretty sure he had less than that). 50 billion / 300 million is around $166 per person. So now every person in America is $166 richer, and the world has no Tesla or SpaceX.