Holding a volatile currency is what's risky. If the seller and the payment provider quickly convert their bitcoins into USD -- as seems likely to be the case b

Holding a volatile currency is what's risky. If the seller and the payment provider quickly convert their bitcoins into USD -- as seems likely to be the case based on the link in Maxious's reply -- then they're minimizing the time interval during which their wealth is exposed to exchange rate fluctuations.