Visitors are you great competitors in the web because they can spend time studying the platform , modules , security and update you are using. The more visitors the higher privilage your site will be attack frequently.
Webdevelopment is constantly changing everyday. If you take a look the evolution of yahoo.com you can determine the dramatic changes they had to update the site from time to time.
Most of the famous top 1000 websites are well organized both frontend and backend. To be organized is to always give a room for innovation for improvement.
When you expand your territories in learning more in webdevelopment the instinct to determine each platform being use in the website can be easy to catch the platform and modules you competitors are using in optimizing their website intelligences.
Again visitors are your greates competitors online because they can duplicate your site and innovate into higher advancement. Always evolve your site with changes to at the leading edge.