Advertising & Marketing.

AKA "crystallising public opinion" & "public relations" (propaganda & psyops).

Especially as from Ed Bernays (who inspired Hitler, Anslinger & Hearst).

I'd say nukes, as they are the only human invention so far that can end all of life as we know it in an instant. I still can't blame the countries who built them as a response to the US wanting to use them to become world ruler, which they absolutely would have done if the other countries didn't also build nukes. But simply as an invention leaving politics aside, fuck nukes.

Capitalism.

Leaded gasoline

Ads.

Slavery

CGNAT, easily

Cross posting

private property

Other people have good real answers, so here’s my joke answer:

Clothes and fire. Humans evolved to live in the climate of Africa, then one day some genius had to invent stuff that let them move to everywhere else in the world, and now thousands of years later, I’m freezing my ass off and my skin is dry for like a third of the year.

Portable speakers

The mc rib

Donald tr*mps spraytan

religion

imperialism, facism, slavery, torturing, ... can't pick one

money

The nuclear bomb, easily.

.....Proprietary software is a very distant second place.

Internal combustion engines.

If we only had the electric motor public transport would've been the norm rather than cars.

We'd be in way better shape now.

if we are not talking concepts or ways of doing things or such and stick to just actually physically made products that are mass produced and widely bought. I thought I was going somewhere but so much stuff is concepts. If you don't have gunpowder there are all sorts of other explosives and not have cars does not necessarily mention not having engines and if you do an engine type then you just have it all under a different engine type. Going to one specific thing I think would not really do anything but make a kind of knowledge hole because something that is ultimately going to be obvious is just not done for some magical reason. Honestly it all comes down to regulation and laws and such. I mean the amish don't have to deal with cars and smartphones even though they exist. Its really on us to use things or not use them responsibly.