1. He lied to the American people and said Iraq had weapons of mass destruction in order to falsely justify invading Iraq causing the deaths of tens of thousands of innocent people.
2. He ignored U.S. laws whenever it suited him (multiple times) as if her were a despot rather than the elected (not really—he stole that too) leader of a democratic nation.
3. He took the United States’ reputation as a world leading country with high ethics and ideals and dragged it through the mud with actions like those cited above.
4. His administration failed in their duties of oversight of the financial markets, and pursued policies of reckless deregulation that rolled back safety in many arenas include workplaces, the environment, and much, much more.
There is so much more. Do a little bit of research and you will see.