You bet your life
In what could be described as the best potential retirement fund, this guy had terminal cancer and a bookie gave him 50-to-1 odds that he wouldn't live a year. He took that bet and won. Twice.
http://news.bbc.co.uk/2/hi/uk_news/england/beds/bucks/herts/8075288.stm
http://news.bbc.co.uk/2/hi/uk_news/england/beds/bucks/herts/8075288.stm