DAMN!!! Popeye beat me to it. That being said, crashes are normally caused by one or more of the following:

• failing to inspect the plane for issues that can cause a failure
• flying in conditions that the plane was never intended to fly in
• pushing the plane beyond it's capabilities
• the ever present "Hey, Watch this"

Granted, there are more reasons that are beyond the pilot's control like engines failing in flight, radio interference(though not as much with the modern 2.4GHz systems), bird strikes and various other things that can happen so a crash isn't always the pilot's fault