How do you get from a fifth-grade coin collection to a $2 billion collectibles giant? Heritage Auctions C.E.O. and co-founder Steve Ivy made a business out of a childhood obsession. He’d been dealing in rare coins when he partnered with James Halperin—another coin-dealing college dropout, who also happened to collect comics—in 1982. Their business grew through the 1990s with the advent of the web, and the timing was fortuitous: As fine art grew more valuable and contemporary began to soar, Christie’s and Sotheby’s ultimately exited furniture, antiques, rugs, and other categories to concentrate on secondary sales in luxury items. In the process, they ceded much of the collectibles market to Heritage.