Greed is valuing material wealth more than you value morals. Some people in Bitcoin are greedy, some are not.

There is nothing inherently greedy about mining Bitcoin. If you are producing value for others and trying to produce value for yourself, then that's fine. It's when you start to value it more than your principles that problems arise.

Because greed is such an individual virtue, there really isn't an effective way to assess whether Bitcoin is based on greed or not. All we can say that it can function in a world where everyone is greedy, and it can function in a world where no one is. Thus, in a world where we have a mix, Bitcoin works and you should really just worry about your own virtue instead of the "morality" of the network.