As someone who spent most of his life surrounded by poverty, but after college found himself thrust suddenly into the ranks of a much higher socioeconomic class, I also experienced impostor syndrome. I was shocked by how fast things changed, the somewhat improbable series of events that lead to my new station, and sometimes found it hard to believe that I deserved my success. However, this was short lived.
From observing my colleagues, I quickly realized that many of them had been born into their socioeconomic class, and either took for granted or were expected by their parents to achieve a measure of success that I had previously only dreamed of. I also saw that many of the people who were vastly more successful than I were not more skilled, rather they had simply been in the right place at the right time. Seeing this really bothered me, since I had never enjoyed such privileges. Why should they deserve success when it was seemingly handed to them through their upbringing or just pure happenstance?
But then I looked back at my old classmates from high school, most of whom were still languishing in minimum wage jobs, somehow managing to work longer and harder than me and never seeing anything for it. The only thing that I could see that set me apart from them, that enabled me to achieve what they probably never will, was my own innate intelligence--something that I was simply born with, something that they could never earn no matter how hard they tried. This realization shook me to the core.
I realized that I was no different than those entitled yuppies with the rich parents, or the lucky individuals who struck it rich by joining the right company at the right time. We all got something that enabled our successes, not because we deserved it, not even because we earned it, but simply because we got it. I realized that if I had something, it didn't matter whether I deserved it or not, because the simple fact was that I had it, and trying to justify why I had it made no difference.
The world does not give people what they deserve, rather "deserve" is simply a concept that we humans have made up in an attempt to justify what the world has simply given to us or what we have managed to take for ourselves. In order to validate our own feelings, we crave an explanation for why we feel good when someone gets something in a way we approve of, or upset or envious when they get something in a way we disapprove of.
I believe impostor syndrome is a symptom of attempting to uphold one's belief in the concept of "deserving" when that belief is in conflict with reality. So I reject the concept of deserving. If I have something, I have it. If I can get something, I can get it. Existence. Cause and effect. That's just reality.