Plug Power (NASDAQ:PLUG) stock is a dicey proposition. The company has never made a profit. In 25 years of business, the hydrogen fuel cell maker has failed to make any money whatsoever for itself, let alone for investors. No matter how much cash has been pumped into the business, Plug Power has failed to generate any meaningful business. Even though it recently announced a billion-dollar conditional loan guarantee from the Energy Dept. that helped send shares soaring it failed to hold onto any of the gains ...