Lark, so much of this sums up my situation!
My deck collection at one time was much bigger.
I have a fault....I get over enthusiastic about something and buy willy nilly just to have...or out of fear it will be not available later.
I go through phases with all of my hobbies, which is why I pop in and out of the AT forums, for months at a time. And when I'm getting back into something, the impulse to BUY is hideous. Fortunately I think I've been through the cycle often enough so now I'm trying to trade my way out of the impulse!
Over the years I have sold or traded at least 70 decks.
And as of today I haven't regretted a single letting go...as a matter of fact like you, I felt district relief when sending some of them off.
Not as many as you, but certainly a lot. I haven't even kept track of what has come and gone. I don't mind - now - letting go of something that I "should" like but don't. I don't want to be guilt-tripped by my own cards!
What I truly hope for is, as you mentioned in your post, that core collection of beloved decks. And the funny thing is, I look at my collection, and already know which ones those are. It's just a matter of taking a breath and letting the others go.
But it can take a while to get past the highs and lows of a deck, I find? Often an early obsession or love can, over time, turn into a great big MEH. Or it's hard to get rid of a deck I once loved but never would want to use.
I also have a fair bit of guilt over being given a very large collection by another ATer. Many of the decks were not to my taste, and those I sold and traded. But there are others, for some reason that are more difficult to let go, even when I don't really see myself using them any time soon. They were hers, and they were loved.
. I am slow.