People Are Never Satisfied
No matter how much we have, it seems that there is always something more to strive for. It is a rare person who is truly content with his life just as it is. However, I believe that a certain amount of dissatisfaction is a natural part of human nature and is actually beneficial to mankind. After all, it is dissatisfaction with the way things are that pushes us to improve. In my opinion, people will always want something more or something different than what they have.
Take Edison for example. He was not satisfied with the knowledge he gained from the books and teachers of his time. He still had many questions to which he could not find satisfactory answers. This dissatisfaction led him to make many important discoveries and they, in turn, contributed greatly to the advancement of mankind. There are many other examples like Edison throughout history. In addition, people are competitive. They like to keep up with others, so when one person acquires something desirable, those who know him will want to do the same. Furthermore, people like to express themselves and differentiate themselves from others. This leads people to strike out on their own in some way and do or invent something new, which in turn leads to a new fad for the others to follow.
For all of the above reasons, I believe that people will never be truly satisfied with what they have. They will always be striving for something new or better, and it is this process that leads to progress. In the end, some dissatisfaction can be good for us.