It's a business that everyone seems to want in on, even though new data show it's awfully hard to do profitably.
In some ways, the enthusiasm makes makes sense: According to a report from IBIS World, a market research firm, online grocery sales grew at an annual rate of 14.1 percent over the last five years and they are expected to grow at a rate of 9.6 percent between 2014 and 2018.
But look more closely at the report, and you see the major challenges these companies will face as they try to make these fledgling businesses viable.
