Why US venture firms can't get rich in China By: CNBC.com News June 13, 2014 at 13:06 PM EDT Despite having about one-fifth the worldwide total of Internet users, China is notoriously tough for U.S. venture capital firms. Read More >> Related Stocks: Apple Baidu.com SP ADR China Mobile Hong Kong Ltd China Unicom Hong Kong Ltd Facebook Google, Inc. Thomson Reuters Corporation Twitter, Inc. Zendesk Inc