Why do people feel so good about posting photos they had no part in?

I understand the concept of, "hey, look at this cool thing I found", but if people want to do that, they can easily link to the source. However we live in a time where people will post pictures online they had no part in producing and aren't of celebrities of any kind and bask in a glory. You even get some people posting pictures pretending its their spouse. I just don't get why this is a thing.