Losing in trading I guess.

Because I risk more in trading than in gambling, so if I lose money in gambling, I'm sure it's not as big as the amount I could possibly lose in trading. For me, gambling is for fun, while trading is for business, so it's like your business is not successful if you lose money on trading.
Yeah, this works for me as well. Because I am more into investing my money and time with trading compared to gambling. Losing in trading is worst because I am pouring my hard work into it, than to gambling that is basically done for sun and with my excess funds.