yup, that's true, but generally xsperf is quite right saying the people who move up the fastest are the ones who are snithces.
In the end, you both are right: To be really successful, you have to give 110% WHILE still being a bit selfish and not worrying about "killing" others to get on wth your career as long as it doesn't violate your personal ethical standarts...
if you find the right mix, you will most probably succeed...