Well yes, you do need to have sufficient funds available, arbitrage is more of a professional strategy than one for beginners. That doesn't make it impossible to do. As for losing when you come to withdraw, that depends whether you got the strategy right in the first place. You need to factor in the trading fees and transactions fees before deciding that there is enough of a price difference to make it worthwhile. If you do all correctly it is one of the least risky trading strategies there is as you are short and long the position simultaneously and therefore perfectly hedged. This means that movements in the overall market will not affect you. As the price comes back together, your profit in one account will outweigh the loss in the other every time. The only risk is in execution error.