The 4 Dumbest Money Mistakes People Make and How to Stop Making Them, According to Shark Tank’s ‘Mr. Wonderful’ Posted by July 13, 2016 Leave a comment on The 4 Dumbest Money Mistakes People Make and How to Stop Making Them, According to Shark Tank’s ‘Mr. Wonderful’ If you make these common budget blunders, multi-millionaire money master Kevin O’Leary says you’re headed for disaster.