The odds of winning any major lottery jackpot are extremely slight  However, the very few people who do win major jackpots receive a great deal of attention from the media
Thus, since most people come to have at least some awareness of events that receive extensive media coverage, it is likely that many people greatly overestimate the odds of their winning a major jackpot
Becoming aware of individuals who have won a major jackpot leads at least some people to incorrectly estimate their own chances of winning such a jackpot.