The answer to that question is, the reasons vary. For some, they might be working on a time crunch. They might not have the time to create something themselves, so they purchase something that will work for what they need. For others, time is money ... it will be more cost effective to buy something than create it themselves. Others might not want to learn how to create their own content. Instead, they just like to create the art and get to the end result. With such a wide range of people, it's a great thing that there is so much content, reasonably priced, to choose from.