Why would a person ever do something like blogging? Why would anyone ever use social media? By uploading personal media to the internet for all to see they are asking (without asking) any to spectate.
There is no simple formula to explain what content people might see daily, or the scope of what they might stumble onto. You could guess the things that a particular demographic might want to read about, or what kind of media suits their interest, or even keywords they might search for in a typical day. Asking these types of questions may give you some ideas about what your hypothetical demographic looks like, but it doesn't give any explicit "yes, you should blog", or "no, there is no reason to blog."
Here's my reason to arrive at a "yes, you should blog" answer. Allowing content to be