Some Advantage of SEO are:

There are people searching for your products or services on search engines
SEO pulls-in quality traffic
SEO traffic is more likely to convert
SEO increases sales and leads
SEO can decrease your cost per acquisition
SEO does not involve any paid advertising
Top SEO rankings provides 24/7 promotion
SEO is a long-term strategy
SEO makes your customers more informed
SEO is more cost-effective than paid advertising
SEO increases the value of your business
SEO will increase your blog traffic
SEO can double, triple, or quadruple your business