It's a common strategy in forex. Like in gambling, it can be highly successful - until you hit a bad patch and run out of cash.
For example, I could open a buy trade for 1 lot. If it goes up 20 pips, I close and am happy.If it goes down 20 pips, I open another buy for 2 lots. If it then goes up 20 pips, I close the first trade at BE and the second at +20. If instead it falls another 20 pips, I open a new buy trade with 4 lots. If it goes up 20, I close trade 1 (1 lot) at -20, trade 2 (2 lots) at BreakEven, and trade 3 (3 lots) at +20.
In theory, if price keeps moving against me, I just open 8, 16, and 32 lots. No matter how bad a trend is against me, it should retrace 20 pips at some point, thus assuring my profit. The fatal assumption is that price will bounce in my favor before I suffer a margin call. It may not happen today, tomorrow, or even next week, but it will happen sooner or later.