Everyone should be skeptical that they can beat the market because it is true, there is overwhelming amount of evidence that few people can do it on a consistent basis, even some of the best fund managers.

Also, I think you picked up Apple for the right reason, even if it wasn't the immediate source of their success. For most of us (non-financial types), it is best to gamble on companies that we are familiar with. I play around with stocks on the side, and it should be no surprise that most of my winners were stocks for companies that I was familiar with (i.e used their product), and most of my losers were from stocks that I picked up after reading a crappy financial advice column.