I see a lot more subtlety here than that. This is already a pop summary of work published in the "Journal of Experimental Social Psychology". Do we need to reduce every piece of information to a 10-word summary?
It is.
They also say you like people more who spend their time and money on you and not on some strangers who need those resources more than you.
Anyway, I just wrote this "summary" because I had the impression the diction was a bit heavy for mere mortals :)
People like you if you wouldn't sacrifice them for the benefit of the group.