I wouldn't consider it gambling because although it involves a lot of speculation, risk etc, it involves knowledge which is something you do not have control of when gambling (specifically dice)
There are different forms of gambling but in my understanding it's divided into two category, these are skilled based and luck based gambling.
The one you are talking is an example of a luck based gambling, of course it's hard to win through luck as the house has the edge and you will never
gonna have a chance to be a long term winner.
In trading, you can develop your skills and for me it's like a skilled based gambling.