"Where is the boundary between curiosity and greed?
How do we find out which things we really need and which are just unnecessary luxury?
How do we find out what knowledge is really helpful and what is only a waste of time?"

These are questions each individual must answer for him or herself, but in many ways I think they are answered simply by being asked. An individual who asks these questions is seeking balance around these issues - questioning his or her own habits, boundaries, assumptions, and knee jerk reactions - and will inevitably find it, although I think it's a continuous process, like balancing on a tightrope.

When human beings fail to ask themselves these kinds of questions, that's when imbalance risks becoming pathological, and can have disastrous repercussions ;)