There are a lot of single word domains I wouldn't own in the top three extensions. Just because it's a single word doesn't mean anything other than it's a single word. Like .pro, .tv, .mobi and .US you have a very few number of people making any money with .CO. The larger holders of these extensions will argue otherwise.
As with most things people place in storage units for years the value of those items are far below the storage costs.
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