I do not think that gambling is like trading, sure they are similar with risk but that is the only similarities they have, the big difference is that day trading has a return of investment while gambling obviously do not have.
I agree with you but it is not the return of investment.
It is not that we always lose in gambling, we do, in the short run. In the long run, it is either we are getting back our money or we are just losing. Mostly we lose in the long run. In terms of return of investment, we can't always do that in day trading since we can lose there. There is a higher risk of losing in day trading since with the fast-changing market, we don't know what will happen.