maybe you are right; but personally, one of the big reasons I started my own business was that I saw really, really good people only made 20%-50% more than absolute mediocres, when they were 10-20 times more productive.
If it were possible to make big bucks without starting your own company would I have continued to work for others? maybe.
The thing is, some people say "Once I have enough, it doesn't matter" and certainly, the $100K/year that your average bay area computer person makes is 'enough' to live on... but double that and you will be able to retire in less than half the time. Retire and work on your own terms, if you like.
For me, that is what getting more money is about. I don't really care about having a nicer car or anything, but it sure would be nice to be able to, say, take a year off and travel, and not worry about what employers would think about the year-long gap in my resume.