Why do we repeat mistakes?

It is quite common that we repeat our own or others' actions or thought patterns that have clearly not led to desired results or a positive outcome in the past. For example, an employee might witness management techniques that affect the company badly and that neither he or his co-workers support. Still, the employee might do the same kind of management when she/he becomes a director.

Some of the reasons might include the following:

We have a tendency to believe that the world is utterly fair. We might think that the past action was required and that it didn't produce as poor result as we then perceived it it be. This is know as just-world hypothesis.
State-dependent retrieval. It is a phenomenon in which we have a hard time accessing a memory of an emotional state that we are currently not in. So, if a poor decision made us feel very unhappy in the past and we are currently happy, we will have an attenuated perception of the past decision's effect on our happiness.
Creating new ideas is more cognitive demanding than repeating the well-known pattern. It takes more energy, time and effort.
We have fear of the unknown. Even though the past behaviour didn't produce good results, its effects are more or less familiar to us. We hold onto belief that the unfamiliar is more likely to produce an even worse outcome.
We can get addicted to what isn't true but could be - we find uncertain outcomes exciting. We know that the past behaviour didn't produce a good result but we're addicted to repeating it as long as there is even a small chance of it to succeed.
Being overly optimistic. We might think that, if we change one small aspect of a behaviour, it will produce completely different or even much better results. If we know that another person's behaviour caused a poor outcome but we weren't otherwise involved in it ourselves, we might believe that we are more lucky and that it won't happen to us. This is called optimism bias (it's also known as comparative optimism).
We don't learn from mistakes enough. A study showed that a past mistake can have a guilt-inducing effect and can actually encourage us to make more mistakes.

Understanding why we are sometimes inclined to repeat the same mistakes is important because by revealing the mechanisms that are responsible for it, we get awareness of what we should work on if we want to make ourselves more psychologically sound, more competent and break free from a circle of inefficient actions and thought patterns.