Here's some research which shows that, while superstitious behavior won't stop events from happening, it does have practical value to people. It won't stop bad things from happening to you - but it may stop you from feeling bad things.
Would you hop on a free flight to Aruba? I'm guessing you would. Now, what if that flight were contingent on a coin toss? If the coin comes up heads, you will be on the plane. If the coin comes up tails, someone else gets your seat. Some of you are now more reluctant to get on that plane.
Perhaps you are thinking of the most famous coin toss in music history. On February 3, 1959, a plane full of musicians crashed in Iowa. The musicians included Buddy Holly, The Big Bopper, and Ritchie Valens - the musician who popularized the song "La Bamba." Valens' presence on the plane came as the result of a coin toss. Valens and Tommy Allsup, another musician touring with the group, flipped a coin for a seat on the plane. Valens won, and died.
The incident became famous, and it's not hard to see why. There's something horrific and fascinating about a life riding on the toss of a coin. Of course, no one is struck by the amazing coincidence of a life riding on the decision to buy a ticket, to go on a musical tour, or to book a gig in Moorhead, Minnesota. All those chains of events led to the same result, but no one thinks of the mundane decisions - just of the coin toss.
A group of researchers, handing out a survey, found that this fascination isn't limited to plane crashes and coin tosses. They surveyed people about their reactions to the goring death of a very young matador, who had been substituted in at the last moment because another matador had to drop out of a fight. Unusual events that led to misfortune, the survey found, were more likely to prompt huge emotional reactions, and lots of "what if" thoughts, than normal events that led to misfortune. Partially, this is because we remember unusual events. No one remembers exactly when they booked a ticket but they do remember a coin flip. If that heads or tails leads them to disaster, they can think back on that one moment. In order to regret your past decisions, you have to remember them.
But this intense emotional response might also be a practical basis for superstitious behavior. If someone takes an unusual, or unexpected, action and it leads to disaster, they know they will regret it far more than they would if they'd just wandered into the disaster without making a memorable choice. On the other hand, if they refrain from taking the unusual action, and they miss out on some minor pleasure because they refrained, they'll probably forget the whole thing in a day or two. By being superstitious about a coin toss - or any other omen or bad luck charm - people might not be making a completely irrational decision based on irrelevant information. They might be thinking about how different scenarios will affect them emotionally, and have decided to hedge against the worst possible scenario.
[Via What Might Have Been.]