Many people believe that SEO is a long term investment and will only increase their ROI after a long duration. My reply to them- Yes Sir, You are absolutely right!!!
SEO is a process that takes a longer duration to deliver results may be for competitive business terms, more than a year or so. But...
There are many overlooked benefits of Search Engine Optimization.
If you are optimizing your business for few keywords, out of which some are highly competitive and the SEO guy tells you, this keyword may reach 1st SERP by an year end. It means, that particular keyword can get top of Search Engines by year end(may be before that) but other keywords can definitely be on top of SERP quiet earlier(PPl usually miss this part). You can always get traffic from other keywords and business too.
The only possible reason I can think of why few people might miss an opportunity to increase their business via Search Engine Optimization would be if-
They are you planning to drift away from their current business by NEXT Year?