Why is it so hard to get rid of stuff?

I must confess: I am a pack rat.
This has mostly two reasons. First of all, I live frugally. Therefore I have a great urge to hold on to stuff, just because I might need it again at some point. And wouldn't it be silly to give away something just to pay money for the same item again later?
Also, I try to live green. So I hate to contribute to the landfill thing. I try to reuse and recycle everything. Often that isn't easy. I don't know if an item can be recycled and trying to find out and recycling it properly takes a long time.
Giving away or selling items is often hard too. I have ads out on Amazon, Ebay, Craigslist and Freecycle. This takes time I often don't have as a 38 weeks pregnant mother of two kids under five.
So stuff keeps piling up. I try to give stuff to Goodwill, since I buy a lot there and keep thinking that I also ought to contribute. But even that stuff keeps piling up, because I usually try not to make the trip to Goodwill for only three items or so.

Often I try to declutter, and I realize I can't let go of things. I used to make jewelry, so I have a tone of jewelry making stuff and material around. I know I should sell it. I have changed and I am not sure if I will ever return to jewelry making again.
But I can't.
There is the nagging voice in my head telling me that I might take it up again and then what?
I guess that all that stuff is somehow also a manifestation of our hopes and dreams. Things you once were and things you want to be or wish you were.