Do not post personal info. How is it okay to post personal information onto the internet if it isn't yours to give out? Who's fault is it exactly if someone posts another persons info onto the internet?

There is a lot of people posting information like full names, birthdays, addresses, phone numbers, ssns, etc onto the internet. Who's fault is it exactly if someone posts another persons information onto the internet? I don't understand, if you have access to someones info onto the internet then it isn't yours to give out, why is it okay to post onto the internet if it isn't yours to give out? It is wrong. Literally why would someone think it is okay to post someone personal info? I would never think of posting someones personal information to the world. I also don't get it, if it isn't your information then you don't have a say whether someone posts your information or not. But how do you know if you are allowed to or not? Shouldn't it be the persons choice whether you are allowed to post or not? Why would they think it is okay? Do they think it is okay to post someone's information without permission? It just makes me mad thinking about it. It isn't their choice to make, if they get caught they are going to say it was me who told them they could post it. I can never in my life think of a situation where it would be okay to post someones information without their permission. It clearly isn't right. Why would someone think it is okay?