I have to be honest, I could not forget a loss quickly when I was still gambling without good control years ago because I did not manage my money well at that time. There were many times when I regret what I did and I could not forget it easily. Even after few weeks or months, I could still regret what I loss. Lesson learned obviously, nowadays I can forget a loss easier although not instantly. I believe it is something natural. I do even doubt that people can forget their loss instantly/quickly although they claim that they do it for fun or what they loss is something that they can afford to lose, but a loss is still a loss and it is normal if we regret it.