No one is saying that white skin equates success, but to close your eyes to the fact that being white (or male, for that matter) has no underlying contribution to any success you enjoy is living in a fantasy world.
I'll contribute much of my success in school/college and by extension career to the subjects I enjoyed and how easily they came to me and my parents' willingness to sacrifice for the betterment of my future. But I don't think anyone is saying those qualities come with race or ***. Certainly not "a lot" of my success being contributed to my ***/race instead of earning it through work, as Omegavegeta stated..
That's nice that you believe that, but it simply isn't true. Society has created gender roles for jobs and you're blind if you think otherwise.
Society may have influence in what paths are expected, but it didn't make me good at it or make me succeed. Just because society says Controls Engineers are supposed to be male didn't make the subject come easy to me. I enjoyed it and was good at it (Naturally good at it). Being male didn't make me good at it. Being male didn't make my parents willing to go without for so long so I could end up in a better position (I'm not from China)
You're absolutely correct in that it didn't make you smarter or understand anything any easier. However, that's not what we're talking about. We're talking about you getting hired. When people think a specific job, people envision a certain person and that certain person is more likely to get the job than someone who doesn't fit that description. It isn't always intentional, but it's reality.
When I worked at McDonald's, people starting positions were determined first by ***, then my race then by attractiveness. All males tend to start in the back, all females tend to start up at the front or drive through. If it were two people of the same ***, then the white people would start up in the front/drive through window. If they were the same *** and race then the more "attractive" person would be up front.
Of course this wasn't official, but it was obvious. In the entire time that I worked there, every black male had started in the grill. I thought this was only at that store, but as you start looking at other jobs, you can see a similar pattern.