Hence, scalping with margin is one of the most difficult thing on trading.
I don't even know what 'scalping' means as far as trading goes, but I would agree that op got lucky with this trade and that it is hard (and very risky) to trade when the market is trading in a tight range like it has been for a couple of weeks.
And yes, we can benefit from the sudden sideways as long as we make a good entry and exit then scalping will go smoothly.
Uh...yeah, that's the key there, making what you call a good entry. This trade could easily have gone bad had the market dropped suddenly. When there's no obvious momentum in any particular direction it's basically gambling when you place an order like this.