Private Keys are NOT Stored on the Blockchain:

[Mitu100@]

Let's break down why and what might be confused with this concept:

Why an "All Bitcoin Private Keys Database with Balance" Does Not Exist:
Astronomical Number of Private Keys: As explained before, a Bitcoin private key is a 256-bit number. The total number of possible private keys (2
256
) is an unimaginably vast number. It's cryptocurrency user database computationally impossible for anyone to generate, store, or brute-force (guess) even a tiny fraction of them.

Imagine a database large enough to hold even a fraction of these numbers, let alone their corresponding balances. It's beyond any current or foreseeable technological capability.
The Bitcoin blockchain is a public, distributed ledger that records transactions between Bitcoin addresses. It does not store private keys. Private keys are generated and held locally by the owner of the Bitcoin (in their wallet).