Reagan was a failure because he gave millions of illegal Mexicans amnesty and permanently turned California, the most populous state, blue. Permanently guaranteeing democrat dominance in that state and beyond, from that point onward to appeal to the growing demographic of non-European Americans the Republicans adopted a leftist social policy and moral framework from which they now operate. Only being distinguished from the democrats by their fiscal policy.
His only redeeming quality was successfully countering the Soviet Union. But what good is a successful foreign policy if domestic policy falls flat?
US presidents appear to have this false precondition that America is perfect with no room for improvement and have literally adopted the Jewish concept of "Tikkun Olam" in a misguided, paternalistic global crusade to 'tame' the world. The irony being that they, the neocons want to terraform the world to align with their geopolitical interests (Israel). In essence they have applied Tikkun Olam perfectly, by setting up a globalist system that supports and subsidises the existence of Israel with negligible benefit to the United States itself.