Brandon — who asked to withhold his last name to maintain his privacy — pays no rent and no electricity bills. His only fixed living cost is truck insurance, which is $121 a month.
"Mint.com puts [my net worth] at $121,532.89 between investments and cash, minus any credit cards I haven't paid off this month," Brandon tells CNBC.
After taxes and all the pre-tax investments, "my take-home pay is about $2,000 a month," he writes. "In the Bay Area, that would hardly cover rent and basic living expenses…if I had them."
"It's a nice reminder that my lifestyle really is accelerating my ability to build the future I want, at no (or maybe even a negative) cost to my happiness," he says.
At this savings rate, Brandon says he could retire by 30 with a little over $1 million.
However, he's hesitant to say he's "retiring early."
"My attention span is way too short to actually retire," Brandon tells CNBC. "What I'm doing is working towards financial independence, so that I can stop working and still afford to feed and clothe myself, living off of my investments for the rest of my life."
At that point, he plans to travel, he tells CNBC. "I'll travel with a laptop, and work on all the personal projects I have going (like my blog), and probably pick up some contract work for fun," he says. "I've seen woefully little of the world, and I'd like to change that."