How Rich is Russian President Vladimir Putin?

Could Russian President Vladimir Putin secretly be one of the richest men in the world? According to journalist Luke Harding, yes. Harding, author of "Collusion: Secret Meetings, Dirty Money, and How Russia Helped Donald Trump Win," sat down with Business Insider to discuss his theories. Harding reveals that he investigated Putin's wealth back in 2007 and wrote a series of articles based on information he received from sources inside Putin's presidential administration.