The man-made object responsible for the most deaths worldwide is the tobacco cigarette. It isn't even close.
Tobacco kills 443,000 Americans a year and 5 million people a year worldwide. This is more than the total number of people killed by cars and firearms combined. Cars kill about 32,000 Americans each year and 1.3 million people worldwide, while firearms kill about 32,000 Americans each year and "several hundred thousand" people worldwide.
100 million people were killed by tobacco in the 20th century. This is more than the death toll from World War 1 (17 million) and World War 2 (50 to 70 million) combined.
From a strictly utilitarian perspective, would there be anything to be gained by, say, starting a campaign of assassination against executives of tobacco companies?
I once got a friend to read HP:MoR after a year of mentioning it. After the first few pages, he googled Eliezer Yudkowsky and within a few minutes was on the Less Wrong discussion section, where he immediately found "Nazis vs Jews" (posing the question "what if Jew-killing is a terminal value for Nazis, and what if there are orders of magnitude more Nazis than Jews, what do you do, from a utilitarian perspective?"), as well as "how to stop people from being creepy at your Less Wrong meetup."
Also, not one, but two My Little Pony Friendship is Magic Rationalist Fanfics.
That was pretty much the end of that.
Not all fanfics are created equally, eh?