While accumulating wealth is usually a long process that requires not only hard work, but also a lot of persistence, some billionaires have made their fortunes rather quickly. In return for their distinctive ideas that changed the world, the world made those young individuals very rich.

This is a compiled list of the world’s wealthiest young entrepreneurs:

Dustin Moskovitz

Just 30, and already the world’s youngest self-made billionaire. Dustin Moskovitz was Mark Zuckerberg’s roommate at Harvard, and co-founded Facebook. Just like his friend and current CEO of Facebook, he never actually graduated from Harvard University. Moskovitz still owns 2.34% of the tech giant, putting his net worth at $8.3 billion.

Interesting fact: Although financially stable, he still flies economy and drives his bicycle to work.

Mark Zuckerberg

Facebook Co-founder and CEO Mark Zuckerberg makes the list with a stunning $35 billion. The world’s largest social network has been acquiring a number of companies since the time the company went public in 2012. In addition to buying messaging service WhatsApp, Facebook also bought virtual reality headset maker Oculus VR for $2b. Note: The founder of Oculus is only 22 years old himself.

Interesting fact: He doesn’t own a TV, doesn’t believe in God and wears the same outfit every day to “clear his life” and focus on “more important matters”.

Jack Dorsey

According to Forbes, the co-founder of Twitter and Square is worth around US$2.3 billion. Still a bachelor, he remains involved in the social network, currently leading the board as Chairman. His daily work is focused on Fintech company Square, which aims to process transactions with customers who pay via debit or credit card.

Interesting fact: Sent the first tweet ever (“just setting up my twtr.”), removed his nose ring when Twitter took off, doesn’t have an office desk and wants to be mayor of New York City.

Elizabeth Holmes

At age 30, Elizabeth Holmes’s company Theranos, focusing on blood testing, is valued at $9 billion after it raised another $400 million from venture capitalists in 2014. Since she owns 50% of the business, her net worth is estimated around $4.5 billion, making her the world’s youngest self-made female billionaire. The Stanford dropout even inspired former statesmen George Shultz and Henry Kissinger to join the company’s board.

Interesting fact: Despite being the youngest self-made women billionaire, Elizabeth Holmes has no other woman sitting on her company’s board. She’s also fluent in Chinese, taking classes after constantly calling Stanford admissions to accept high-school students. Ultimately, the head of the department agreed to test her fluency, accepting her shortly thereafter.

Robert Pera

Although worth $2.8 billion, Robert Pera is not as known as some of his peers on the list. Having taken his company, Ubiquiti Networks, public in 2011, he became a billionaire at age 34. The idea for the company which provides internet access to more than 10,000 customers within a 36-mile reach came from his work at Apple, where his ideas bore no fruit. He ultimately left the company and started Ubiquiti Networks.

Interesting fact: Pera admired Steve Jobs so much, he was the reason for taking on his first job at Apple. Being also a sports fan, Pera has also recently acquired a 25% stake in the NBA’s Memphasis Grizzilies.

While it is an impressive list, sometimes the road to success is a long one. The lesson to learn here: start young, dream big and work hard.