To build a community of passionate followers who care about your brand & you nurture this community over time, so they proselytize others on your behalf.
Obviously, there are other “objectives” to social media if you are merely using it for leisure. But if you are a company or brand, then the above should be a top priority.
It’s how you fuel word of mouth (henceforth WOM) which is the ultimate boon when it comes to marketing. Social media, when executed correctly & consistently, allows tremendous “reach,” particularly if you’re offering a product or service that people really want.
That last sentence is key. At the end of the day, WOM will not be achieved unless your offering is truly great. In today’s competitive world, your product or service must be excellent, or iterating on the way to excellence, in order to stand out from the crowd.
But if you’re creating, or in the process of creating, a truly “must have” offering, then social media marketing is a fantastic set of tools to explore to fill the “top end” of your funnel.