Bitcoin has unleashed a wave of speculation in El Salvador since its adoption as legal tender last month. Uber drivers, waiters and shop owners are day-trading the cryptocurrency on their phones, buying dips and selling rallies with a government app that comes pre-loaded with US$30 worth of bitcoin. The government’s new digital wallet, called Chivo, was designed to facilitate bitcoin transactions, but the ease with which users can top up their balances and switch instantly between dollars and tiny, fractional amounts of the cryptocurrency makes it a perfect tool for speculation. In the capital San Salvador, many large chains such…