There’s not a single trader or sophisticated investor I have spoken to who believes Ryan Cohen , the CEO of troubled video-game retailer GameStop, is really going to buy eBay . And yet, I can’t count this guy out – and neither should you.  Yes, there are plenty of reasons to doubt. EBay is five times GameStop’s size. The meme investor cult that has followed 40-year-old Cohen doesn’t extend much beyond the fevered swamps of retail stock picking.  Cohen’s recent disclosures about his bid also