used by Bitcoin Core to store your private keys, transaction history, and metadata. Standard Locations: %AppData%\Bitcoin\wallets ~/Library/Application Support/Bitcoin/wallets ~/.bitcoin/wallets Recovery Process: To access your funds, you must place the wallet.dat file into the correct data directory of a Bitcoin Core installation and allow it to sync with the blockchain Bitcoin Forum How to Protect Your Own Wallet bitcoin/doc/managing-wallets.md at master - GitHub

Why 2021? This is the most critical part of the keyword. By 2021, Bitcoin had already seen several massive bull runs (2017, late 2020). The value of BTC had soared, making old, forgotten wallets potentially worth millions.

Or more specifically:

The ethical questions multiplied. If one could access private keys from a careless backup, should they notify the owner? Could they safely disclose the leak without enabling theft? Responsible disclosure in crypto was messy and rarely rewarded. Alex felt the old tug of utilitarian duty: prevent harm where possible.

As of 2021, the FBI, Europol, and Interpol actively monitor public dorks. Placing a known stolen wallet (e.g., from the 2016 Bitfinex hack) into an open index is a classic sting operation. Downloading it implicates you in receiving stolen property.

: If the file is unencrypted , a thief can simply download it, drop it into their own Bitcoin Core data directory, and sweep the funds.