The best way to start an "upper class career" is to be born into the upper class. Good luck getting into finance or consulting if you didn't go to a top tier university. And it's not small matter -- even if you have the right background -- to get that job at McKinsey or into a Harvard MBA. You have to be extremely smart and strategic in your career choices, and not slacking off in college, either. Then, to advance and do well, you have to put in long hours and do very good work.
In this day and age, I think it is hard to argue that there is an easier, faster or more forgiving path to economic success than software engineering and programming. The author of this article wouldn't even have a chance to get started in any the of other lucrative professions you mention with his 2.9 GPA.