The win has nothing to do with the money you make. It's the rush of the moment, as you alluded to.
It's the same for drugs and alcohol. Your brain becomes obsessed with the apparent need for cortisol and adrenaline. It doesn't take notice of time, meaning the money you've earned or saved (past) and where you may end up (future) doesn't come into it.
Memories are funny things. They are experiences which combine emotional charges with sensory based evidence. They then re-presented themselves brought the emotional charge. The are not recalled, as such; more reconstructed.
You can't really tell what's real and what isn't and your 'instinct' is to keep trying to recreate that experience by doing what your senses picked up on: where you were, what you saw, what you did, etc
It's why we often forget about the negative stuff that happened in a relationship for example, and become obsessed again with the 'joy' that was created, even of it was just that one time.
This is becoming even more serious now with online gaming and pornography.
The psychologist, David Greenfield, had done some great work on this.
http://virtual-addiction.com