1. Harry S. Truman (1945-53)
Despite being a relatively popular U.S. president, Truman was a terrible businessman.
His first failed venture was a men’s clothing store the he co-owned with a friend. The store went bankrupt and Truman lost everything. His next (and perhaps biggest) mess-up was a bad investment made in the zinc mining industry. The failure threw Truman into deep debt that he would carry with him to his grave.
In the end, Truman and his wife ended up moving in with his mother-in-law. Strangely, despite his personal financial struggles, Truman is credited to this day with stabilizing the U.S. economy during his time in office.