What's the Purpose of Blogging?

In my opinion, Blogging is a very interesting concept of new new media. The reason I say that is because I don't really understand what is the point of blogging? A blogger writes about anything he or she wants whether it is a movie review, a personal top ten list of songs, cheat codes to a video game or how well the day went. Somehow, there will be at least one reader that will read the blog. However, the trick isn't about writing it; it's about getting more readers and making sure they come back. A creative blogger will come up with ideas that interest the majority of people so they will actually come back. But what does the blogger get out of all of this? Most bloggers seem to do it for fun or because they love to write. Nowadays, bloggers can even make money from advertisements using Google AdSense or even Amazon Associates. Now that is an incentive to blogging!
Fun fact about me: When I was in high school, I decided to create a Xanga. At first, I was doing it because my friends had one and I wanted to try it out. The problem was I didn't have the motivation to write every single day. Eventually, the blog became an outlet for my emotions. Whenever I was upset and wanted to vent, rather than bothering my close friends, I would write it on the blog. Of course, I didn't make this public (only my closest friends could read it), but it was a way for me to get my frustrations out. Since that's how most of my friends started blogging, that became my definition, which isn't the norm today.