Luck is a hard thing to prove. There is no real thing we can call luck, but we can create a real object and transfer luck to it, such as a lucky penny or a lucky charm.
These lucky objects give the feeling of a security blanket. They provide an illusion of control for the person who believes in them.
A positive attitude towards life makes it seem like more happy events happen for a person.
While it is not rational to believe in luck, understanding the psychology behind it can explain why some people seem to be successful while others can never get to the top.