Social skills are not mentioned in your statement. Your statement says only that those with poor grades are more sucessful than those with good grades. I can't think of a possible reason why what you say would be true. I am quite confident the opposite is true.
There are numerous studies that show college graduates make more (significantly) than high school grads. Those same studies will show that high school drop outs make less still. Of course those with Cs and Ds are less likely to go to college and more likely to drop out.
Further, students who do poorly often do so because they are lazy or unmotivated or intellectually lacking. Are those traits likely to make future CEOs?
When controlled for all other factors better students will always be more successful than poor ones. Any argument to the contrary seems ridiculous.