One of the greatest gift that nature endowns human beings with is 'common sense'. It seperates us from the rest of the animal kingdom. We do not just response with 'reflex' muscle or action. We can project our thought and visualize the outcome of certain action or courses that we might want to take base on our past experience or the experience of others.
But how come so often we abandon our common sense and leave ourselves in precarious situation? Let me try to think of a few reasons.

1. Was not trained to use this faculty when one was young. Too many children have their daily needs taken care of by adults around them and never learn to problem solve. When they grow up, some would find another person who would take over the unpleasant jobs from the previous adults in their lives, so they can go on pursuing only what they want to do. Others would do only things as they are told and find themselves being victimized (be it real or unreal).

2. We may be caught up emotionally, brushing away the red light that keep blinking in our head.
3. We may not have estimated ourselves correctly according to our abilities. Thinking we can handle more than what it takes.

4. Pursuing only what one thinks is pleasant. Do not want to take time to think of the outcome or the possible unpleasantness. Avoiding pain can actually bring on more pain.

Conclusion:
Knowledge or abilities are nothing, when they are not applied with 'common sense' or 'wisdom'.