having been an adult at that time I can tell you that it was because the good ole USA had a near decade of losing from Vietnam through gas lines through a major recession and he basically said F-this, we are the best country on the planet and let's act like it. He did a major (and long needed) reform of the tax code, he reversed the national mentality of we suck to we don't suck or at least don't suck that much and his policies led to the demise of the Soviet Union.
the biggest downside is he launched the era of massive deficits
other than that, yes he was a celebrity