You should look at this as a good thing. You can use them to see what work and what doesn't. Adjust your product and add features that your competitor lacks. Any market worth while will have competitors.
For the same reason no one will be able to beat wikipedia. It's a LOVED company. People will flock to craigslist till it turns on it's users. Case in point ebay.
You have to keep in mind that the app store was a response to people jail breaking the iphone and installing 3rd party apps. Apple never wanted developers messing with it's precious device but they finally gave and look what happened.