Tony Robbins, renowned life and business strategist and New York Times bestselling author, has dedicated himself to spreading personal finance literacy across America. As a member of CNBC's Financial Wellness Advisory Council, he's continuing to share his insights and key strategies to help improve Americans' financial future. Throughout his career, Robbins has had the opportunity to interview some of the smartest investors on the planet, including Warren Buffett, Carl Icahn, and Ray Dalio. When it comes to investing, the one mantra they tell Robbins over and over is that most investors fail simply for psychological reasons. In other words, Robbins says, our own brain can be our biggest liability. According to Robbins, these are the three biggest mistakes that will derail any investor's success.

Mistake No. 1: Confirmation bias

Mistake No. 2: Overconfidence

Some people just get so overconfident, he says, especially men. "Research shows that women actually invest better than men do when it comes to trading, because men trade more often. They're overconfident," he says.

Tony Robbins David A. Grogan | CNBC

Mistake No. 3: Negativity bias