You are maintaining a site and growing a business. You need to devote ninety percent of your day to marketing. This doesn't leave much time for mastering the intricacies of search engine positioning. It's likely the pros are going to beat you every time. With each passing day it is more difficult to obtain top positions with a given keyword.
Competition continues to increase for any phrase selected.
And more and more professionals continue to climb on board with no end in sight. Not long, if the keyword is of interest to others. Because lots of people are looking for the top spot, including the pros. Your page will be analyzed in detail until a way is found to beat it. At some point, other submissions will out rank yours, and you will begin to lose ground.