This message can be interpreted in a variety of ways. It can be looked at as (literally) not everyone is going to see how worthy you are, or it can also mean that you may not be recognized for all of your accomplishments.
The first interpretation seems to apply to the relationships developed among people while the later applied to career and personal growth events.
Although most of us will not be recognized for our accomplishments, it does not mean that they are minute or thoughtless. The lesson in this is believing that what what ever you are attempting and whoever you are is good enough. You do not constantly need other recognition to believe that you are something special.
In the perspective of building relationships, people come an go. Some are here for a lifetime while others are here for a season to teach us short lessons. The people who do cannot see your true potential and great value are probably "seasonal."
Just remember that the ball is in your court and at the end of the day your thoughts and actions are what matter.