

Because it’s immoral and it would be dual standards unless you take away from all who “didn’t earn it”, like disabled people or people temporary without jobs. Those also get money for basically existing.
There’s also the problem of incentives, if you encourage taking from those who have, you prevent new people from possibly starting businesses because why should they, if it will basically be taken away from them? Better to be jobless or do some minimal non-useful work and get money for nothing from the wealthy. You just move the problem from A to B but you didn’t solve it.
Many issues with that also. First - wealthy people just move their wealth overseas, as most wealth is actually not in physical goods but freely movable virtual papers and money.
Second, if the rule applies to all, it would leave a lot of children without the base which their parents worked their whole life for, as they would probably not afford to pay tax on a house they would inherit.
And third, inheritance doesn’t mean anything really, but how someone can manage it. Being wealthy is easy. Becoming wealthy and staying wealthy is hard. Plenty of kids who destroyed empires their parents built. If the kids can manage the wealth and build upon it, why punish them for having good parents?