"I have never let school interfere with my education." --Mark Twain

As a young child, I was taught that the path to success looked something like this: Study hard. Go to college. Work even harder. Marry a nice person, have a nice life, work until you can retire, and then enjoy the fruits of your labor.

Sounds familiar, right? I bet you've heard this advice your entire life--that if you can afford to go to college, you need to do just that. And if you can't afford it, you'd better work hard for a scholarship! People without college degrees make less money and don't get the good jobs.

At least, that's what we're told.

Even as the cost of a college degree has skyrocketed, leaving American students with more debt than ever before, conventional wisdom tells us college is a must. We're borrowing more to fund our education, too; U.S. students now owe more than a trillion dollars in outstanding student loans.

But you have to go to college. You'll fail without it.

Someone should have told these nine tech billionaires.

Each person on this list dropped out of college, yet every one of them went on to make not only millions, but billions in the business of technology. Would they have been better off with a college degree? It's hard to imagine how.

Check out these billionaires who share a trait that should have held them back in life: They dropped out of college.

1. Michael Dell--Dell founder

Net worth: $21.9 billion

Was Michael Dell ever cut out for college? At just 8 years old, he applied to take his high school equivalency exam. His parents made him stay in school, but that didn't slow Dell down. He focused instead on after-school ventures and, at 14, he learned that he was pretty skilled in fixing computers. Dell gave college a go at the University of Texas. His parents hoped he would become a doctor, but he ended up building a $25,000/month computer business in his dorm room. I hope they're not still disappointed in his career path!

2. Elizabeth Holmes--Theranos founder

Net worth: $4.5 billion

School: Stanford

Elizabeth Holmes went to Stanford for chemical engineering; it was there that she filed her first patent and traveled to Singapore to work on the SARS virus. Just ahead of her sophomore year, however, Holmes left Stanford behind and went after her dream of pioneering personalized medicine. Today, she's reimagining the American health care system, with her revolutionary blood-testing technology that runs diagnostic tests with a single drop of blood.

3. Mark Zuckerberg--Facebook founder

Net worth: $33.3 billion

School: Harvard

It's a good thing Zuckerberg at least gave college a shot. Were it not for his time at Harvard, he may never have met his roomies Eduardo Saverin, Andrew McCollum, Dustin Moskovitz, and Chris Hughes, who helped him launch the first iteration of Facebook from his dorm room.

4. Steve Jobs--Apple founder

Net worth: $11 billion

School: Reed College

The iconic founder of Apple might be the best-known college dropout-turned-billionaire on the planet. It's not like he didn't get anything out of his time at college; Jobs's inspiration was that he wanted a computer interface as pretty as the calligraphy on his college campus posters.

5. Bill Gates--Microsoft founder

School: Harvard

Net worth: $80.5 billion

Gates started at Harvard in 1973 but dropped out two years later. While there, he told professors he would be a millionaire by the time he was 30. Always the overachiever, Gates became a billionaire at 31.

6. Jack Dorsey--Twitter co-founder

Net worth: $2.3 billion

School: Missouri University of Science and Technology and NYU

Dorsey attended Missouri only briefly before transferring to NYU. He'd been interested in computers and programming since his high school days back in St. Louis, yet he dropped out before receiving his degree. Instead, he made his way to Oakland and met up with Biz Stone and Evan Williams. Stone was an executive with Dorsey and Williams's first company, Odeo, before coming on board with them to start-up a simple site called Obvious, which was based on 140-character messages. Sounds a lot like Twitter, huh? That's exactly what Obvious became.

7. Evan Williams--Twitter co-founder

Net worth: $2.4 billion

School: University of Nebraska-Lincoln

Like his co-founder Dorsey, Williams' felt the call of the start-up and left college before graduation. In fact, he left the University of Nebraska-Lincoln after just a year and a half. Odeo was a start-up success for the pair, but it was Twitter that made them both billionaires. Williams still serves on Twitter's board, but now spend most of his time working on his blog platform, Medium.

8. Larry Ellison--Oracle founder

Net worth: $46 billion

School: University of Illinois Urbana-Champaign and University of Chicago

Ellison left the University of Illinois in his second year without taking his final exams, after the death of his adopted mother. He tried a term at the University of Chicago, but ended up moving to California. It was a good thing he did! After a few false starts, Ellison founded a company with two partners--that company was renamed Oracle Systems Corporation in 1982.

9. Jan Koum--WhatsApp founder

Net worth: $6.8 billion

School: San Jose State University

Koum embodies the American Dream. After emigrating to the U.S. at 16 with his mother, he became a math and computer science major at San Jose State University. However, his work as a security tester during college led him to a position at Yahoo. He dropped out to work at Yahoo for nine years, before starting WhatsApp.

Now, if you're adamant that a college degree is necessary, let me suggest that you probably don't want to go to Harvard or Stanford. (I know, "Are you crazy, Larry?")

I'm serious--get yourself in to the University of Pennsylvania. Of the super successful who have graduated college, UPenn has produced the most self-made billionaires currently alive in the U.S. Charles Butt, Steve Cohen, Elon Musk, and Ronald Perelman all got their degrees from Penn.