Self-made millionaire Graham Stephan is the first to admit that he's "extreme in terms of saving," he tells CNBC Make It. "No one is more frugal than me."

The 29-year-old YouTube star and real estate investor earns up to $220,000 in a single month, but still refuses to spend money on things like coffee and designer clothes. 

"I'm probably extreme in terms of saving and frugality, and I think a lot of people probably find it pretty intense," says Stephan, who estimates he saves 99% of his income. "But I love it. I love the challenge of saving and trying to handle my money well and grow it."

That said, he doesn't mind spending on things that matter to him. That's why Stephan recently purchased a $19,700 watch. Last year was the 50th anniversary edition of the 1969 Zenith El Primero A386, a watch he inherited from his grandfather.

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"My grandpa got [the El Primero] as a parting gift because he was doing some work with Zenith," Stephan tells CNBC Make It. "He never really wore it. He put it in a drawer and it just sat there for like 40 years. And then when he passed away, the watch was accidentally going to be thrown out with a whole bunch of junk because he had never worn it and it wasn't working anymore."

Stephan found it before it got tossed, thought it looked cool and decided to get it repaired. "Little did I know what it was," he says. "Once I started doing research on it, I realized, Wow, this has a lot of history behind it. It's a really rare watch." It happened to be one of the original self-winding chronographs, which "really changed watches," he says. "This was the first of its kind when it came out."

He started wearing it "on the days where I feel like I need good luck," he says. "Which is most days."

Last year, Stephan Googled the watch to see what it was worth. In the process, he found out that Zenith was offering a 50th anniversary edition of the watch — and they were only selling 50 of them. Stephan got the last one, for $19,700.

"It was definitely one of the most expensive things that I have spent money on," he says. "But the thing with watches is that a lot of them can make great investments and most of them end up keeping their value."

While the purchase was "part-investment" for Stephan, "I really bought this just because it is very sentimental."

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