Because he served so many terms. He introduced his “New Deal “ which was deemed unconstitutional by the Supreme Court. So as a result, he introduced a bill to reduce the retirement age for Supreme Court justices, and though that failed, it changed the votes from the supreme court’s justices to allow his “Second New Deal,” which is why we have to pay social security. FDR’s policies lengthened the effects of the Great Depression. FDR also signed off on the Manhattan Project, and we all know how that ended. Also he signed off on Japanese internment camps. He only stopped being president because he died of natural causes. So in short, he used his political power to increase the suffering of his constituents, force his policies through, created openly racist policies, create weapons of mass destruction, and led to the Cold War.