Obama had Iran signed up to and complying with a nuclear non-proliferation treaty with unprecedented levels of UN oversight in Iran and creating an economic environment conducive to liberal progress.
Trump blew up the deal, imposed even more sanctions (against the wished of every US ally), assassinated Iran's #2 illegally while he was mediating with Iraq, got the US kicked out of Iraq, conceded Syria to the Turkish and Russians, betrayed the Kurds who fought ISIS (resulting in thousands of ISIS prisioners going free) and promised to commit war crimes against the Iranian people.
Trump's done more to embolden opponents of the US in a 3 days than Obama managed in 8 years.