There is a danger of theft, and the risk is to everyone, not just the parties to this big transaction. The risk is this: 1. A malicious syndicate gathers a bil

There is a danger of theft, and the risk is to everyone, not just the parties to this big transaction. The risk is this: 1. A malicious syndicate gathers a billion dollars of bitcoin and sends it to themselves 2. In a short period of time, like a few days, the syndicate exchanges that bitcoin for non-bitcoin assets 3. The syndicate spends tens or hundreds of millions of dollars to fork the chain, backing up the ledger, so that they own the billion dollars of bitcoin again So anyone accepting bitcoin for non-bitcoin assets for the next week or so is at risk. It doesn’t have to be a single transaction, though; this danger occurs whenever the transaction volume on bitcoin gets above the cost of mining.