Uranium ore... Because it would be cool to tell your friends you have it.
A large enough supply of Rare earth, high grade uranium ore contains "Uraninite" for Geiger counter / radiation detector test source ~38k CPM! by LifeTech http://www.amazon.com/dp/B00CQ9LLR4/ref=cm_sw_r_udp_awd_zELgtb02S8NAJ
Best Buy is closing stores because they have a lot of redundant real estate (the press release mentioned having Best Buy and FutureShop locations practically next door to each other). Target closed stores because they couldn't supply them adequately and shoppers had no reason to go there, so they were losing millions of dollars. That's a very different scenario.
As for Amazon, a) they're losing tons of money, so Wall Street is no longer as willing to overlook their faults as they were in the past, and b) I think people are reaching the limits of when and how online shopping is useful. The reason people purchase online is when it's not available in a store, or it's cheaper than buying it in the store. But now most retailers offer price-matching, so that takes away a lot of incentive. If you have a choice between seeing the item in person and buying it immediately, vs. waiting a few days and hoping UPS doesn't drop-kick it all the way to your doorstep, then you might not be willing to wait.
Amazon has an advantage in that they sell everything (you can buy fucking uranium on Amazon, for chrissake) and they have a robust drop-shipping and third-party function. Target and Best Buy aren't selling mattresses, bedroom sets or power tools (or uranium), that's not their niche. And that's fine, retailers don't have to be everything to everyone. But at the same time, for the items which Amazon does have competition from brick-and-mortar retailers, the incentive to pick one retailer over another (which is to say, price) is dwindling.
Keep in mind that a lot of the ongoing maintenance of brick-and-mortar stores is to keep an eye on traffic flow and purchasing patterns. If a store doesn't get enough business to justify its presence, why keep it open? The shift in retail for chains that also have a significant online presence is to keep the profitable stuff on the floor, to carry a decent if incomplete variety of those items, and to move most of the loss leaders to the online channel. That's why, when you walk into a store today, you'll see a ton of tablets, phones, cameras, TVs, computers and appliances, and accessories for all of the above, but you see only a comparatively small selection of music, movies and videogames. It's silly to dedicate 3/4 of the sales floor to music and movies when they actually lose money. But websites are cheap as hell, so it's a lot easier and more sensible to maintain a complete media catalog online and ship on demand, than it is to buy a bunch of inventory and hope it sells (especially when we know people aren't buying hard copies anymore, because this is 2015 and people stream now). It makes more sense to keep the most popular electronics and appliances on the floor, and then offer an expanded selection online for people who might want a special color or model, and are willing to wait a few days. Inventory and real estate are expensive, and you want to make sure that you're dedicating your square footage for the items that give you the best return.