People talk about the "Sports Illustrated cover jinx", and even a similar EA video game cover jinx, where making the cover precedes a period of underperformance.

I think a similar effect could be claimed for being called the next Buffett. There is a long list of investor casualties after such a comparison (including the ones you mentioned).

Most recently I'm thinking of Bill Ackman, who was on the cover of Fortune last year with the title "Baby Buffett"... right before a painful 20% tumble.