Social media marketing or SMM has many different definitions.
Since you are asking this in a black hat SEO subforum, I'm assuming you're talking about SMM service providers that provide social proof.
You can easily be forgiven for thinking:
"If I hire somebody to artificially increase the views of the videos on my YouTube channel, how does that make me money?
Those fake views don't translate into more AdSense money."
But here's how social proof works.
When was the last time you saw a video that has less than 100 views?
Be completely honest now.
Tell us what you assumed about the quality of that video.
Assuming that the video is several months old and it has only managed to attract maybe 50 views, what are you subconsciously thinking when you see the view count?
If you're like most people, you would assume that the video sucks.
It's not worth watching.
You're completely normal if you think this way because this is how most people think.
It doesn't really matter how awesome the thumbnail is or how catchy the video's description may be.
It also doesn't matter whether the title got your attention.
You're just fixated on the views because if you're like most people, you're busy.
There are so many things to do and places to be.
And here you are looking at this video with everything else looking good: the title is great, the thumbnail is awesome, and the first screen is good.
But you're hesitating because of the views.
The same goes for subscribing to a channel that has barely any subscribers.
At the back of your head, you're thinking: "Is this really worth my time?"
When YouTube channel owners hire SMM service providers, they get the social proof that they need.
You no longer have that excuse of saying:
"Well, this only got zero views and the video has been around for six months.
The video must suck!"
SMM providers take that away from the equation, and this is the reason why a lot of YouTube creators who go on to develop big, organic followings became successful.
Don't think for a second that a lot of the big names on YouTube never used SMM services in the past.
You'd be fooling yourself.
The need for social proof is that powerful.
It doesn't matter how awesome your videos are.
It doesn't matter if you really know your stuff.
You have to have social proof, and that's why there will always be a market for this kind of service.
