Marketing phrases like “personal brand” come and go, and are mostly the work of marketers who believe to own something, you must re-name it.
Go back decades before such buzzwords pervaded our lives and you’ll find the foundation of this concept was more simply called your “reputation.”
A good reputation comes from your work and your interactions with your community.
You have one, whether you want it or not. Whether you care is up to you and your goals as a photographer.
I have a hard time believing most photographers consider their reputations. I look at their blogs and the consideration given to advertisers over readers. I look at their Twitter feeds that have become broadcasts, rather than conversations. I look at their Instagram feeds and see a stream of consciousness, instead of considered examples of the work that makes them proud.
It seems those most worried about building their personal brands have long ago forgotten about their reputation.