Your "glass is half full" discussion depends upon LEGO releasing more of these sets...which is always possible. It's my opinion this set is done in the US and soon everywhere else from what I've heard and seen. For arguments sake, let's say it is retired. You have the perfect storm coming for STAR WARS LEGO sets with the new movies coming out. You will not see another Star Destroyer or Super Star Destroyer released for a long long time in UCS form...Why? Because you have the Slave I coming out in a few months, which will fill another UCS slot withe the R2-D2, X-Wing and Sandcrawler still in production. This should hold you over until late 2015 when the new SW movies hit the screens. Along with the new movie, you will get NEW ships, thus new UCS sets.
Comparing the SSD to other "large" sets is not a fair one IMO. The SSD is an iconic set. Only the 10030 and 10179 matches it's size and display attributes. I see the future value of the SSD very similar to the 10030...and in a much shorter time. If the set retires now, $1500 is not out of the question Christmas of 2015. That is how special this set is, along with the added interest of the new STAR WARS movies thrown in as a multiplier. Am I bullish on this set...you're damn right. If things go right, there will be many happy people who took a chance. There will also be mad people who didn't, but that is a bonus to those who did. The $400 price tag weeded out the people with limited budgets, which could be a huge benefit to those with deeper pockets.
Everyone needs to make their own investment decisions. Discussions here are just that...discussions. There is nothing guaranteed or written in stone. My vision of where this set is heading can be derailed if LEGO releases more SSDs or there is a worldwide economic meltdown for example. If a person cannot pay their mortgage and food bills, they should not buy any LEGO set as an investment. Not one. Pay your bills and feed your family first. This is a business/hobby for people with extra discretionary income. But for those who have some extra cash laying around, this set will reward you better than any available LEGO set on the market or recently retired. Just my 2 cents...