Paypal has Charge Backs and how do you handle the price fluctuations and differences every minute or seconds? Would you be able to make a profit?
PayPal allows chargebacks, true. Often they resolve the dispute in the seller's favor. Sometimes this is automatic (i.e. requiring no input from the seller) and sometimes it is necessary for the seller to present the digitally signed contract and photo ID of the buyer. It does happen that the buyer (read "scammer") wins the dispute. In this case, the 50% profit guarantee program kicks in, the seller is reimbursed (up to a point) and the fraudulent buyer is perma-banned from xCoins. It is impossible to eliminate charge-backs using the current system, but the risks can be managed.
Regarding price fluctations, unless the price moves by >15%* between when you buy and when you sell, you profit. Best to think of this as an arbitrage system - I would recommend users pay at least some attention to what's happening and maybe keep enough $ on an exchange to re-purchase what you sell.
* I say 15%, but in reality, due to fees and commissions, your profit will be a little lower. You can use this promotional code when signing up to reduce your fees:
hel7lyHope this helps a little.... happy to answer any other questions if I can....