Got you. But human greed and social engineering do not follow mathematical models.
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But if you create 100 than the greed will be 100 time less and people will not like to risk their jobs/career for that small amount.
That's true. But you can't social engineer some information out of someone who doesn't has the desired information (in this case: the private key(s))
The employees of binance (or any other exchange) do definitely not have the access to the cold wallet private key. That would be a big blunder.
You'd need to invest quite some time and effort to gain access to the private keys (circumventing physical / digital security measurements etc. ).
And in this case, it again doesn't matter whether it is just 1 or 100 private keys.