I disagree. Luck may play a role in one's success, but it's not the deciding factor. The problem is that people like to play off their success as just "being lucky". Why? Because this answer is a lot quicker and sexier than explaining to someone how they spent countless hours working their ass off to get where they are.
Have you read Warren Buffett's biography, The Snowball? Sure, Buffett caught some lucky breaks, but the man has essentially spent his entire life completely engrossed in investing. Anyone who claims Buffett is just the luckiest investor alive should really take a closer look at how the man has accomplished what he has.