Why do people make more than one Facebook ?

I noticed some of my friends and family have more than one Facebook account or delete their old ones and make new ones. I only have one I have no reason to do that. My best friend deleted hers she made a new one in memory of her sister I guess because her sister died. My other friend who's the daughter of my favorite rock star deleted her old account also made a new one I don't know why. Some of my cousins have 3 accounts. My other favorite singers cousin has 2 accounts her mom has 4 she had to keep making them because she keeps getting hacked. Why do people make more than one account ?