my dear I actually think you need to make risk management to avoid the loss of many due to the high risk involved in forex trading.and 2% for the trade is a safe point to keep us from losing capital or margin call.so we can trade with little to consistently generate profits without a hight risk. Yes My dear friend this proverb is true that" no risk no gain" so if you earn money from forex market you must take risk to earn profit but it dose not mean you take such risk that your account will be dabble or zero so 2%_5% is perfect, thanks.