There are two ways to build the biggest building...
1) Build the biggest building
2) Rip everybody else's building down
Having said this, ripping everybody else's building down makes no difference to you, except maybe to your ego.
In life, there is plenty of success to go around, so you needn't worry about everyone else's building.
In fact, competition from those around you helps you grow!
Another angle I can come at this from:
If you have something figured out and someone confides in you for help - you may have put weeks, months, or even years into getting to where you are now, which may cause you to keep your cards close to your chest.
At the end of the day, sharing what you know has no effect on you, but you'll be pulling someone else up with you.
Why is this so hard? I know it is for me at times.
I firmly believe that sharing what you know and pulling people up with you can only have a positive effect on you in the long run.
I know it has for me, without seeking anything in return, returns always come.
So I challenge you, next time you hold the cards and have the opportunity to pull someone up... do it.
Give it a try, even if it's hard - maybe one day it will be the best investment in yourself you could have made.