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 haven’t helped his cause. His uneven and sometimes evasive interview on CNBC has been universally panned, including his laconic response to questions about how he plans to finance the deal.  There are plenty of reasons to doubt GameStop CEO Ryan Cohen’s pursuit of eBay. But don’t count him out yet.…