Yes, but not to the point where it impairs you.
-Teaching others helps you learn really well. Its one of the most efficient ways of reinforcing knowledge. (processing facts and stuff helps you reinforce it)
-If you help others, they'll help you back. Maybe share resources and help you with problems you might have. Its not just one sided!
-Being surrounded by smarter people lifts up your game. It increases competition (a big source of motivation) and raises the standards you hold for yourself.
-At the very least, it gives you 'mark insurance' if you mess up your externals! (due to the way all that internal ranking shebang works)
Anyway, why have a crab mentality where you help only yourself and sabotage others? Is that the kind of mentality you want to carry through your whole life and your career?