The world's greatest accidental murderer

Mistakes are essential for growth. Not to sound too much like a motivational speaker here, but how can you learn what strategy doesn't work without failure. It's just part of the process. However, some mistakes don't start as mistakes. They disguise themselves as boons and become burdens over time. Anyone that's ever dated can attest to this phenomenon. 

The same concept applies to ideologies and technology. At one point, forceps were commonly used during the birthing process and seemed infinitely more reasonable than a wholly "natural" birth. Now, forceps are only used sparingly due to the number of birth injuries attributed to them. There are several cases where an innovation that appeared helpful initially ended up having disastrous consequences, but few are more damaging than the ones mentioned in the video linked above. 

The YouTube channel Veritasium talks about Thomas Midgley Jr. and how his discoveries unintentionally led to several deaths and environmental disasters. You know what they say about the best-laid plans, right?