^uh not necessarily true and i suppose its how you define consistent.
no system is full proof or infallible but (shitty example) you can sometimes hedge your risks by knowing that if its a 80/20 trade, if you trade 100times you will make 80 and you accept that as a managable loss.
or you can just watch market forces close enough to know what system will work and adjust accordingly.
there are a LOT Of things that work
and work realllllllly well
but only a handful of people know them and when a bunch of people start using it the market 'knows' and things adjust.
its like time travel theorists, if you touch something in the past how do you influence the future.
very similar, if a bunch of people start practicing a trading activity the shit will shift.
so there are a lot of things that work WELL (notice not perfect but well) but you have to know how to adjust.
i'm really just a beginner but i've had consistent enough "luck" to know that I can probably make a living for myself trading but i dont just trade forex, and i wouldn't ONLY invest in the market. real estate, precious metals, etc. like Wu Tang Financial said, "You needs to deversify yo' bonds N***a"