I am entirely sure how it applies to gambling, but in your normal work life there is a confirmed theory that people perceive losses much harder on a scale from 1 to 10 then gains. For instance, if your boss raises your salary from 2000 to 3000 and three months later cuts it by 200 to 2800, research shows that people rate the loss higher in terms of an emotional scale than the former pay raise. So I guess when you win amount X in gambling, you feel alright and it was an ok day, was fun to watch the game. But when you lose the same amount X the day feels completely shitty, often times people even freak out and want to win it back. I guess it is similar with gambling in some sense. A better example might be if you win 100 in a bet and you afterwards lose that 100 again in another bet on the same day, it feels like you lost something on that day even though in total you didn't.