Let me explain. According to FB's rules, one person can only have one personal profile account. Having more than one puts you at risk of getting all of them shut down, I assume.
Each person's profile has certain information that can be hidden from certain people. For example, you can hide your age from everyone or only let certain people see it.
However, some things just simply can't be private. For example, if you change your profile picture others can see it.
While you can control who sees what you type, you can't control who sees what others type - even on your page. For example, someone comments on your profile picture and says "you look just like your Uncle Tom" and tags Uncle Tom everyone can see it and now knows about your Uncle Tom. You can delete all the comments on your profile picture but that wouldn't be nice to your friends and family that commented.
This lack of privacy is one reason I have never taken part in a FB business group. I simply don't want strangers to know too much. Even though I know privacy on the Internet is basically null and void these days, at least I try to not lay it all out on a platter for their taking.
And, I try to follow the rules of whatever site I'm using.
So, how do you protect your privacy or you don't care?