Why did Tom Lehrer really stop performing?
Most likely even though Lehrer was "a hero of the anti-nuclear, civil rights left" and covered its political issues in many of his songs and, even though he shared the New Left's opposition to the Vietnam War, and advocated for civil rights, he disliked the aesthetics of the counterculture of the 1960s and stopped performing, The hippy-dippy counter-culture was not his crowd.