Is greed bad?
It certainly can be a source of suffering. If we want something and can't get it, it creates negative feelings. Or if we want more than we need and somebody who really needs it can't get it because of us. But is it actually bad?
Our bodies as well as our minds have evolved to the current state. Everything we have must be good for something. Or, if it's not good in itself, it must be a side effect of something good for us. What is greed good for?
Greed keeps us progressing
It makes us want what we see in others. As kids we want the same (or better) toys as other kids have. We wanna learn to do things our parents do. It's our greed that keeps us getting better and better by making us have / know / feel what others have / know / feel. Maybe when the greed is positive we can call it curiosity, and only when we want too much it's called greed. But where is the boundary?
I would like to make a metaphor here. Let's look at the computer. When we start it, some predefined booting procedure begins loading some basic programs like operating system and when it's done the computer is ready to use. You can do anything with it, run any program which can be run.
Curiosity makes us acquire things and skills which allow us to live in the same way the booting procedure starts up the computer which allows us to use it.
What would happen if the booting procedure didn't know where to stop?
It would be loading more and more programs cluttering up the memory, producing unnecessary data, which would fill up the hard disk, until the point when the computer would be completely useless.
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?