Yes, crypto-currencies easily solve that part of the problem. But, you left out everything below it. Like:
- A person have a smart phone
- A person keeping said smartphone
- A person being able to maintain an identity
- A person having the ability to remember that its a new day, they have more money.
- A person understanding the meaning of money
- A person spending the money on blow and not food.
- A person knowing what to do if their normal routine breaks down
- And a person being robbed every day
(If every vendor accepts bit-payment. Then all you need to do is have a front that sells something, then your goons, take your machine and go shake down some undefended oldies for their daily bit-transfer)