Why can’t on-chain transfers be reversed?
Wallet software only checks whether an address is formatted correctly. It can’t tell who the address belongs to, so a transfer to the wrong person’s address can still go through.
Irreversibility is one of the costs of decentralization: there’s no central authority that can alter the ledger, and no one can reverse a transfer for you.
By the way: $BTC is at 77500 (24h -0.26%).

This is not financial advice. Make your own decisions about buying and selling.