Science fiction legend Robert A. Heinlein was the Guest of Honor at MidAmeriCon, the 1977 World Science Fiction Convention, held in Kansas City.
People loved Heinlein or hated him. Perhaps, more properly, they loved his outspoken opinions or hated them. -- as you can tell by the cheers and (occasional) boos. One thing you cannot deny, he was a powerful and popular writer who helped shape science fiction.
Give him a listen. Noted fan and writer Wilson "Bob" Tucker performed the introduction.