The bible calls us to celebrate with the joy and success of others. We should delight in the success of those we know.
Often as people we act as if the success of our brother in some ways makes our success less. It as if the successes only have value in comparison.
We need to learn to see our lives in community. We can do more with others than we can do alone.
We often seek value in our accomplishments and this is the issue. Our ultimate value is in God. If we see everything in relation to God then we see that he is the one who gives success.
We should rejoice with the successes of others. Alone we are weak but together in Christ we are strong.