Didn't we go through this before? Maybe at Autopia? I'm not a student of this car, but when people buy cars to hold, in the way you're describing, they generally need to be able to foresee that it will be a collectible car, so these tend to be special editions, like Indy Pace Cars, or something like a last-year Firebird, or something that is predictable will become a collector item. I don't know if in 2005 someone said to themselves "you know, I'm going to buy an '05 STI because some day somebody like Monza Red is going to come along and want to buy this"...20 years from now.
So that's the other thing, let's say someone did this, bought the car not to own it, not to drive it, but to save it to sell for big bucks later....how long would they wait to do that? 5 years? 10 years? Probably not 17-20 years, when it could possibly be deteriorated enough to no longer be drivable. Think about the cooling system, the brake system, the clutch hydraulics...with 20 year old fluid in them, possible corrosion, etc. Old rubber in the tires, hoses, suspension bushings, etc. I'm not saying that all that stuff is bad, just saying that if someone was sitting on a car like this, it's something they'd have to think about.
It's always possible there is a "barn find" somewhere, or that someone had the foresight and is still sitting on one of these, but it seems like an exceedingly small possibility, especially that someone here, with our very small active community (but bigger than Autopia, LOL) would know of one. If this is your favorite car, I would find a used one in good shape, or a used one in bad shape and have it restored, then at least you could be driving one instead of pining for something you'll likely never find.
I'm sorry if that was harsh, I went through this once, trying to buy a favorite car of mine (not a Subaru), and all I found was disappointment--ones that were so rusted out they were ready for the scrap yard, or ones that were fixed up in ways I didn't like...I never found one that was a good fixer-upper or one that I liked the fixing. Of course that was in the days of newspaper want ads, not internet searching, so YMMV.