Your competitors may optimize their sites as a result of which your web page rank may be lowered.
There are constant changes and improvement in Search Engine Algorithms.
The visitors often change their search and online buying patterns.
There may be a change in the market share of the search engine.
Only a few years ago, Meta tags were the key to traffic growth. Today, link building is of much greater importance. Search engines continuously modify and update their algorithm to try and improve their users’ online experience; therefore, companies that don’t adapt lose the valuable ranking they worked hard to build.