Both EA's and manual trading can be profitable.
Not every profitable manual system can be a profitable EA, e.g. one with discretionary factors.
On the other hand: it does not act on emotions; if programmed correctly it is less prone to error; and an EA is very quick at decision making.
Also, You try doing what an EA does, calculating support and resistance levels, calculating stop loss based on these levels, then calculating trade volume based on the stop loss and risk, scan prior price action and indicator values looking for a trade signal, check the trade is acceptable (e.g. price is within the previous days range, etc), then send an order: all within one tick. This is a huge advantage with scalping strategies.
I personally use both EA's and manual systems. I am working many hours a day trying to create my own profitable systems.