I completely agree with you Go_Blue, but I think that what you are describing is a second stage of the process. In the first stage, people often tilt specifically because of that same reason, because they hate losing. You have to mature from that first stage to the second stage as fast as possible, or else you are screwed.
For example, in the very beginning of my poker "career", I was tilting like a monkey, not because of the money I lost, but because I couldnt take losing to complete idiots who, in my view at that time, did not deserve to win ANY hands with such play. It was exactly what AllIn-Mclovin explained, coming from chess background I just was not used to losing if I was playing well or better than my opponent at least. I think that to a lot of people that is specifically the reason for tilt, not the money. We all have this inherent understanding of justice, or fairness, and we often tend to get upset if we view something as unjust or unfair. Inn poker, well, there is no such thing as fairness or justice
So one has to completely reprogram himself, at least while he/she is playing, and that is not always very easy thing to do