There was a chap on the Beeb the other day who won about six million quid a few years back. He said he got loads of begging letters. He ignored them all, but kept them.
Two years later he was contacted by The Guardian who were doing a piece on lottery winners. He gave them the begging letters and they researched them.
Most were from chancers, some from genuine people with various problems but two were from people the Guardian estimated to be worth 10 million quid or more!