People make bad choices all the time for many different reasons. Usually, “it seemed like a good idea at the time” is at the top of that list.
But by definition it wasn't a bad choice (or a mistake) if it seemed like the right choice given the information available at the time. Unless you have some sort of crystal ball the rest of us don't.
A choice that turned out badly after reflection of hindsight was not in fact good. At best, it was ignorant; at worst, negligent. Regardless, unavoidable; as you surmise, no one has a crystal ball.