Privacy is one of those issues that you rarely care about unless it affects you personally [or someone you know]. Truth of the matter, there are individuals [in the wild and some you may know] who are attempting to access your private data and knowing how that data is accessed is the most importantly part of defeating data thieves.
Why someone would steal your data is as varied as the type of persons who would want access to your data. What you think is harmless data can be quite useful for an Internet marketer, black hat hacker or jilted Ex [gf, spouse, former friend].
I ran this "Hot On Your Trail' video in a previous post but I found it very informative and useful to think about how careless we are with our personal data. Mobile data is the easiest data to access because we install apps that use the API's of both social media networks and/or mobile operating systems which give them full administrative access to your devices [in most cases].
You don't have to be a network admin or work for the Geek Squad to go through your devices and see who has access to your device to review their privileges. Do they really need the level of access you authorized on your various devices?