The foreign exchange market is a zero sum game in which there are many experienced well-capitalized professional traders (e.g. working for banks) who can devote their attentions full time to trading. An inexperienced retail trader will have a significant information disadvantage compared to these traders.

Retail traders are - almost by definition - undercapitalized. Thus they are subject to the problem of Gambler's Ruin. In a fair game (one with no information advantages) between two players that continues until one trader goes bankrupt, the player with the lower amount of capital has a higher probability of going bankrupt first. Since the retail speculator is effectively playing against the market as a whole - which has nearly infinite capital - he will almost certainly go bankrupt.

The retail trader always pays the bid/ask spread which makes his odds of winning less than those of a fair game. Additional costs may include margin interest, or if a spot position is kept open for more than one day the trade must be "resettled" each day, each time costing the full bid/ask spread.

According to the Wall Street Journal (Currency Markets Draw Speculation, Fraud July 26, 2005) "Even people running the trading shops warn clients against trying to time the market. 'If 15% of day traders are profitable,' says Drew Niv, chief executive of FXCM, 'I'd be surprised.