Many of us, instead of competing with ourselves, are competing with others. We don't want them to be more successful. We don't want them to gain something that will make their lives better. If we don't have it, then they shouldn't have it either. That's why we don't share updates with them. We won't give them the tip, the contact, or the opportunity that could better their career.
This is a syndrome that is very common among us, and it is not the way to grow.
Real growth isn't about making sure nobody outpaces you — it's about becoming better than you were yesterday. Someone else's success was never subtracting from yours. There's room enough for everyone to rise. The moment you stop competing with others and start competing with the person you were last year, you'll find you have far more energy to build, and far less need to hold anyone back.