This is an excellent question. There are two things that are important to growing a channel; authority in your niche and personality. People will come to you looking for that thing you provide; whether that be entertainment or educational they need something and they have clicked on your thumbnail to get it. If they subscribe and stick around it is because the style with which you presented your entertainment/education suited them and they enjoyed your personality.
Once they have done so they are a subscriber. But it behooves you to take as many of these subscribers and turn them into fans. A subscriber will leave a like on a video and watch occasionally. A fan buys t-shirts, joins your Patreon and tells their friends about you.
The way that you go about turning subs into fans is to acknowledge them. And the best format is to provide them with an opportunity to be a part of the conversation. So mentioning them in a video is nice (but be mindful you can't do that to 1,000 fans). That is the real value in Social Media. Instagram and Facebook are not about growing and spreading awareness of your channel... that is just another account you are trying to grow. Rather, these social media platforms are an opportunity for you to communicate to your fanbase on a more personal level. Give them behind-the-scenes access to you and what you do. Interact with them.
This is how you turn subs into fans.
