By the nature of the technology, there's no double spending on a blockchain. Because every node has the same database. All and every one of the miners maintain

By the nature of the technology, there's no double spending on a blockchain. Because every node has the same database. All and every one of the miners maintain a copy of what's essentially the same DB, the same distributed ledger. But there are plenty of stolen keys and seeds for wallets and if someone gets your wallet, all your money will be moved to someone else's. This, sadly, happens frequently.