Jimmy Buffett hasn't had a Top 20 solo hit since "Margaritaville" in 1979. He hasn't even released a new album since 2009. He performs maybe 40 concerts a year at most. Still, according to CelebrityNetWorth.com, his total net worth of $400 million puts him just behind such musical icons as Paul McCartney, Elton John and Mick Jagger. How does he do it?