I think you're missing the point that grcumb was making, which I think was a good one. I don't believe he was arguing anything like, "If you want to optimize your chances of success, drop out of school and don't get a diploma." He was responding directly to the quote, "most of the jobs with a liberal arts degree involve asking 'Do you want fries with that?'"
I think what he was saying is something more like, "You have no ground to be so glib about other people's lives."
People who work in service industry jobs deserve some measure of dignity. People who never got a degree can still go on to do amazing things. There are people who have no connection to "STEM" fields who have made huge contributions to your life without developing software. And finally, liberal arts degrees do actually have a use.
There are no guarantees that you will be successful in any case, and there's always a vanishingly small slice of the human population that makes it to the top of their field. But who said that was the point?
If you want to make movies for example, you could pursue that. Maybe you'll be a complete failure. Maybe you'll make something great that's a commercial failure. Maybe you'll make an absolute piece of crap movie that's a commercial success. There's a very small chance that you'll ever be rich and famous as a result.
If you want to make software, you could pursue that. Maybe you'll be a complete failure. Maybe you'll make something great that's a commercial failure. Maybe you'll make an absolute piece of crap application that's a commercial success. There's a very small chance that you'll ever be rich and famous as a result. And so what? Pursue what you want to pursue. If you just want to make money and live a comfortable life, then do some research and figure out whatever career provides that, and be prepared if demand for that job dries up, because that can happen to any job.
But in any case, there's really no reason to be a glib, condescending asshole about other people's lives. There are a lot of good, hard working people out there who are making good use of their liberal arts educations. Some may even have a job that involves asking the question, "Do you want fries with that?" If you're ready to condemn them all as 'losers' because they don't write software for a living, then you're an asshole.