Here's an example of poor decision making that I'm certain involved
a lot of planning with many educated adults.

Placing black rubber mats on a playground for children.

The mental focus was obviously on protecting the children from falls,
but very little consideration was given to the fact that the black rubber
would heat up in the sunlight to extremely high temperatures that
could almost instantly burn skin.

A little child ran out barefoot onto the mats and was immediately
and severely burned.

Sometimes our best efforts, intentions and thoughts don't produce
the best results.