What do you think is the greatest invention of all time? Why? Are there any inventions you wish had never been made?
One of our earliest inventions, one that defines us as human -- Human Symbolic Languages, is also our greatest. Like all innovations it had its costs including hidden costs which are always so numerous and so large that that they would make our ancestors regret their inventions if they could only see the consequences years and generations and millenia down the road. Language separated us too far from nature. made us too different from other creatures, no longer fully participating in the "web of life." We are now in danger of talking ourselves and every thing else into extinction. Still i don't know what we would be like without language -- less "interesting" for sure.
All of our other inventions have been even worse and it is hard for me to think of a single candidate for "worst". Perhaps agriculture, which introduced inequality into human experience on a truly large scale. Jared Diamond ranks it pretty high and i find him hard to argue with. If spiritual suffering can be included along with economic, social and physical suffering, all of our inventions have caused more grief than good,