Scalping is possible. EURUSD moves up or down 10-30 pips hourly on average. GBPUSD moves even more, but the problem is many scalping systems are tend make positions against the trend. When there's a breakout, huge loss from 30-200 pips can occour. In other words, it is possible to make profit by scalping in short-term, but once in a blue moon, a single striking loss will blow out the scalping account. Another main of problem of scalping systems is how far SL should be set. 30 pips SL is many times more than the targeted PL (6 times of 5 pips PL), so that means the scalping system must have at least 6 winners in order backup a single hit of SL! What if 30 pips SL hit 3 to 10 times in a row?