The problem is that 'coin' is not a useful analogy and it makes things hard to understand. Coins don't exist. Only balances do. What you have is a balance (the

The problem is that 'coin' is not a useful analogy and it makes things hard to understand. Coins don't exist. Only balances do. What you have is a balance (the number of 'coins'), but coins don't have an identity (as they don't exist). What one can track is the transactions. So if you send (part of) your balance to another account, that can be seen. If that account sends on a similar amount, that also can be tracked. (Even if you split it between multiple accounts by sending to multiples of them.) The only way you can lose sight of the money if goes to an account that has a (relatively) large number of incoming and outgoing transactions. That can be a person actively paying and earning in BTC (and then you caught whoever stole the money) or a mix. It collects incoming transactions from a large number of addressess (accounts) and then sends these out to a large (but differing) number of other addresses. All you see is constant incoming and outgoing transactions of different values, that add up to (almost) 0 over a long period of time. But you won't be able to correlate them (and no coins exist that could have an identity, just balances). EDIT: Side note - the way actually BTC works, they don't store your balance (as, I think, ETH does), i.e. the balance of an address (account), only the transactions. The balance can be calculated from the sum of all the transactions for that specific address (incoming ones add, outgoing ones subtract from it).