In five years, Grant Sabatier of "Millennial Money" went from having $2.26 in his bank account to $1 million, thanks to a side hustle that he turned into a lucrative consulting company and to smart investing.

"As soon as I began this journey, I looked up the best-reviewed personal finance books on Amazon," the now 31-year-old tells CNBC. Since, he's read over 360 personal finance books and "the best book on money, period," happens to be the first one he picked up: "Your Money or Your Life," by Vicki Robin and Joe Dominguez.