One common cause of their reluctance to embrace social media is the belief that because it involves computers it's primarily a technical process, and that you have to be a tech-head to get into it. But this is just not true. If you can write an e-mail then you've got all that you need to get going on Twitter, Facebook, and other social networks. Sure, there are a lot more things you can do with technical know how. But you certainly don't have to be any kind of a geek to get going.
Even if they don't have this misconception about it being overly technical, I think a lot of people fear it simply because it's new and somewhat mysterious. So they assume that if you are to market something on it you'll need a whole new skill set; that you have to be an expert in its use. But the truth is that you don't need to be an expert in social media marketing to get going and get some benefit. You just need to be an expert in what you do. And if you are in business, dealing with problems and challenges in the field day in and day out, odds are that you are exactly that. And what you need to do is show (as opposed to tell) other people this on those social networks. You do this by connecting with others in your niche and sharing good useful info with them -- without going the hard sell.
Remember, it's called social media for a reason. The whole point of it is to enable people to socialize around a common interest. Ironically, even when people fully comprehend this, some of them think it's this very factor that is what makes it not worth pursuing. This is because they think that business should be business-like. They believe that you don't want to draw your personality into things too much. So when they get on these platforms they go into a kind of corporate mode and immediately start talking business (that is, offering or suggesting their services). This almost invariably doesn't work and so they decide it's not for them.
The trick is in being yourself, while being mindful of your business goals. You're an individual seeking to make genuine friendly connections with other individuals in the same field. If you do this a whole bunch of good things can then develop. They might eventually buy stuff from you (particularly if you're in B2B). They can also lift your profile by sharing your content, and they can help your SEO by linking to your site form theirs (less powerful than it used to be but still beneficial).
I know this sounds a bit vague and non-linear. But that's the nature of it. It's a human process. It's about relationships, communication and trust. And these things go by their own timetable, and in their own way. You can't force them too much. You have to let them develop organically.
Considering that so much of business is about effective time management and getting the absolute best possible results from whatever activity you're using, this arty-farty, touchy-feely aspect of social media is a cause of great frustration to many. As a result a whole new industry devoted to measuring social media ROI has developed recently.