In a nutshell the answer is a lot! You can make $5 a day or One billion in a day. Yes it has been done before. On the 16th September 1992 George Soros Made $1 Billion Shorting the British Pound. One of the most legendary trades of all time: a substantial bet that the British Pound would plummet in value. In hindsight, the trade looks like a no brainer.
Whilst George Soros made $1 billion in profits while bankrupting the Bank of England. This event cost the British Government over $3 billion and saw a massive transfer of wealth from the British tax payers to Soros and his hedge fund.