Of course no-one disrespects other's privacy, and sure this is none of your business, but curiosity is also natural, and for some their curiosity on other people is stronger than others. For those, they might don't understand why a natural tendency is perceived as intrusive, and they will be confused. For me in the past, this confusion invokes more questions, and the cycle will begin.
I still don't think curiosity on other people is harmful, but my life lesson is that it's also natural for others for not having strong curiosity. In their natural point of views, this might be perceived as intrusive. Knowing their personality is crucial, and with time you will know when and how to ask to satisfy your curiosity.
Think of the people you will ask as a small Stack Exchange community. There are two kinds of question that get popular. The first kind asks from curiosity, but it evokes controversy. They're still good questions, but some will disagree with it. The second kind not only asks from curiosity, but also shows the desire to really understand what's going on. The curiosity is not anymore peripheral, it is indeed the one that everyone wants to see it. And this will evoke their curiosity.