I don't have any investment in bitcoin-trader.biz. Still I'm amazed at how little creativity detractors show. For example, it is easy to have revolving lines of credit for fiat. There are also multiple ways of moving fait and you can even move by using other cryto currencies. There are fees and spreads that cut into the profit, but that isn't as much an issue if you can trade a multiple of your funds in a day. It is also possible for prices between exchanges to narrow or reverse in a day.
On creativity: What about the myriad ways a hypothetical arbitrageur could leverage his or her trading?
*Reinvesting some of their steady, fabulous profit until arbitrage opportunity has diminishing returns (no cost!)
*Bank loan, home loan refinance, etc. (~5%)
*Equity investors/partners (could be quite low and risk-free to arbitrageur)
*Credit card cash advance (~20%)
*Loan shark (~40%)
*Payday loan (~200%)
*Paying dozens of people 0.5-3% everyday and updating their balances appropriately (~620-3000%)
Not only is the last option the most expensive, it's the most labor-intensive. Literally the only reason someone would do that is if they want the ability to take the money and run.