Social media is where your target audience is. Apart from maybe a couple of rare exceptions, people of all ages, interests, and socio-economic statuses are on social media. Every popular Social Media platform has a bigger reach than all TV channels combined.
To answer this question, let's first take look at what Social Media Marketers do:
These are just to name a few responsibilities. So do you need to hire a specialist? That depends on your budget, and your ability to provide yourself these these services on top of the other responsibilities that comes along with being a business owner.