Ralph Nader has been many things: lawyer, consumer-rights bulldog, political activist and perennial third-party presidential candidate. He has now added a new title to his business card: fiction writer. His latest book, Only the Super-Rich Can Save Us!, is a 700-page populist fantasy in which a small group of billionaires and media moguls — led by Warren Buffett and including Ted Turner, George Soros, Bill Cosby, Yoko Ono and Phil Donahue — pool their massive resources to reform the U.S. With the help of a $15 billion war chest and a p.r. campaign starring a talking parrot, the group successfully...