Why does people share their lives on social media?

So I’ve always wondered why people post every little thing happening in their life on social media, is it the need for other peoples approval? Praise? Comfort? Knowing someone cares? I don’t see the reason to do so as in my opinion, people do not care about you and your life. Ofc there’s celebrities and influencers (which I still don’t get) that people watch for some reason. I have family in another country and a stepmom, let’s call her “Lisa” she posts EVERYTHING about her life, like nothing is secret and I cannot for the life of me understand why she does it, do you guys have any ideas or suggestions into why this behavior occurs?