Graham Stephan can afford to buy nearly anything he wants: The 29-year-old earns up to $220,000 in a single month and is on track to make a minimum of $1.6 million in 2019.

Still, the YouTube star and real estate investor is careful with his cash. "I've always enjoyed the aspect of not spending money, even as a kid," he tells CNBC Make It, adding, "I end up saving about 99% of my income, just because my income is so high, and I keep my expenses so low."