Jihan Wun runs Bitmain Technologies Ltd., the world’s dominant producer of cryptocurrency mining chips. Founded 5 years ago, Bitmain booked $2.5 billion of revenue last year, and Wu along with his cofounder together own about 60 percent of the business. While Bitmain has few direct comparables, applying a multiple similar to that of publicly traded chipmakers such as Nvidia Corp. and MediaTek Inc. would give the company a valuation of about $8.8 billion. That would make the co-founders’ holdings worth a combined $5.3 billion, according to the Bloomberg Billionaires Index.