The Monty Hall problem

[Alex K]

I wonder how often we make suboptimal decisions in real life because we overlook this effect!

What effect would that be?

Imagine you have to make some choice, like buy a car or choose a course of action out of several possible, and you know that one of them is probably wrong. Then you are shown that one of the other possible courses of action which you have not decided to pursue is also successful. Will you change your mind or remain with the course of action you had decided upon.
This may be vague, I just want to propose that variations of he monty hall problem can appear in everyday life in abstract form, and it could influence the way we deal with new information if we understand it properly.