Options trading
When it is known fact that most people specially options buyers loose money, however a great chunk of this take position both side .
Suppose an option is being bought and that does not go in profit for sometime the same put buyers started to think that market will not fall now without knowing the fact that what is risk reward and then takes entry since market has already gone up so much neither it fall nor it goes up but fully sideways.
Theta Decay kills and eventually premium gets zero