Moses Lin says he'll never consider going back to college, despite being one semester shy of graduating with a bachelor's degree.

In 2011, Lin joined the U.S. Marine Corps and, after his enlistment ended in 2014, enrolled at Vanguard University of Southern California.

"I knew that if I went to college and took a traditional route, I'd be hundreds of thousands in debt," he says. "I just didn't want to start my life that way."

Lin started a YouTube channel during college, where he posted acoustic covers of pop songs, and began teaching guitar lessons for money. By the spring of his senior year in 2017, he decided to quit school and give a full-time music career a shot.

Now, after years of building his own business as a traveling wedding guitarist and investing his earnings into real estate, Lin, 31, is on track to make $500,000 this year.

Lin says much of his success comes down to honing one important skill.

"I think learning how to learn is the most underrated skill," Lin tells CNBC Make It. "As an entrepreneur, I've learned video editing, CSS coding [and] all these random talents."

When it comes to "almost anything creative, I know how to teach myself that, and I know how to find the information, or find the experts to figure it out," he continues.

Lin taught himself everything when it comes to building his business as a wedding guitarist. He charges between $6,000 and $15,000 for gigs, and couples cover travel expenses for himself and his team, which includes a sound engineer and production assistant.

He has also recently gotten into coaching to help other musicians grow their businesses. He charges $1,500 per hour-long session and has mentored clients in Ireland, Singapore, Dubai and across the U.S.

Another key to Lin's success is setting ambitious goals and telling everyone about them.

When CNBC Make It spoke with him two years ago, he set a goal to have a net worth of $1 million by the time he was 30 — he reached that goal a few weeks shy of his 31st birthday.

"I've always been a fan of: make a crazy goal, tell everyone what your goal is, and then you have to make it," he says.

Getting other people involved in your goal-setting builds a sense of accountability. Plus, since a lot of his work is referral-driven, repeating his goals out loud helps him get connected with people who can help make them happen.

"If you don't set a goal, you're just clocking in," Lin says. "You'll look back and think, 'Oh, I think I did OK,' but you have nothing to measure against."

Lin currently has eight income properties in Little Rock, Arkansas, and nets $2,500 per month in rent. It's not enough to live off of, but his goal with real estate is to increase his net worth over the long term.

"I spend less than I make, my net worth has appreciated with my portfolio and I'm happy doing what I want to do," he says.

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