The aim justifies the means.
I don't completely agree with this statement, as there are different aims and different ways of achivements. If you want to be rich and decide to rob a bank, for example, I don't think that this mean of achieving the desired is the best one. In this situation it is more appropriate to work as hard as it possible or win in the lotery :) Or if you want to get a promotion by downgrading your workmates it is not also the way you should behave. Unfortunately, the present economical situation makes people betray each other, steal and expose the colleagues and friends.
I can say that I am a confident person and I always invest time and effort in achieving the goal, but I also think about others, I prefer to achieve the aim without any harm to my family and friends, first of all and to myself. However, not all people do the same and I have been a victim of such things several times and I know from the first hand xperience that there's nothing pleasant in it.
Actualy, it is very pitty to realise that there are people around you who, being very kind and helpful to you, can one day betray or use you to their own benifit.
Of course, sometimes I also use people's help to get what I need but I never dissemble or betray people.