Ryan Cohen always has big ideas. Some like Chewy.com, the successful pet products online retailer that he co-founded and eventually sold for $3.35 billion, turn out to be great ideas. And some, like his aborted takeover attempt of the original Bed Bath & Beyond, turn out to be big busts. Now Cohen has his biggest idea ever: GameStop, the gaming retailer he is CEO of, is trying to buy eBay, a company three times the size of his. To do so will take an enormous amount of financing (try $9.4 billion in cash and up to $20 billion in debt), which is often the kiss of death for any retail business. And eBay is no big Hit either this week; it has zigged and zagged its business strategy for decades with varying degrees of success. Same as Cohen, who has also played the meme-stock scam as well as anybody. He always aims high; it’s just that very often his aim is not very good.