However, there are authors who tried the professional route, couldn't find enough interest and then published on their own. For example, Amanda Hocking started publishing her paranormal series last April on Kindle. This was after trying her best to do things the professional way. Her ebooks have since been a hit and because of her success, she's gotten an agent and a publishing deal.
Thing is, this almost never happens. She worked hard to get to where she is and a lot of it came from word of mouth. While she could go on self publishing and marketing her own work, it's taken a lot away from doing what she likes most-writing. So, once a deal was on the table, she took it earlier last month (think that's about right, the timing could be off).
There are a handful of others like her who tried the professional route, had not interest and self published. Thing to keep in mind is success among independent publishers is so rare. There are a few members here who have been successful, but again, they worked extremely hard and continue to do so.