It's been noted for a while that the price of Bitcoins sags each weekend. That's an indication that new money is required daily. You can still trade Bitcoins on a weekend, and people do. You can still mine Bitcoins, and people do. But you can't wire transfer in money from a bank.
if it were always true that the price goes down on the weekend due to inability to wire fiat money to an exchange, the smart traders would spend the weekdays wiring their money in preparation to buy only on the weekends when prices are low. This should level out the weekend dips in the long term
in other words if it was always obscenely profitable to do something simple, everyone would be doing it and nothing else, and then it would no longer be profitable