Theory 1. At some point Rossi decided to attempt a large scam. He somehow talked Focardi and some others into this. Focardi said something like: "I'm tired of being a poor Italian university professor. Let's make money! How about we rob a bank?" Rossi answered, no, no, look, we can easily fool idiots into believing we achieved cold fusion. Look at Steorn. Focardi: Hey that's a great idea, let's do it!
And they went on to design advanced deception machines. Then they started doing demonstration after demonstration to lots of people, including some very knowledgeable ones. Investing huge amounts of money, they built a giant complicated fake machine with lots of pipes, wires, control systems, diesel generators, pumps, hydrogen bottles etc. They are now just waiting for the gullible investor checks to clear before leaving Italy and escaping to some remote tropical paradise to spend the money on alcohol, cocaine and escorts, and possibly come up with their next scam, possibly after undergoing plastic surgery to change their appearances. Theory 2. Cold fusion is being researched by scientists since 1989. Conferences take place every year and tens if not hundreds of papers have been published. Lots of scientists replicated the effect. Some of them reproducibly obtained small amounts of excess energy. One enterprising technical-minded guy from Italy came accross a university professor working in that field. They agreed to attempt to develop a prototype for a commercially useful reactor. After a couple of years they succeeded and started performing public demonstrations. Due to general human stupidity and the immense amounts of money, power and reputation vested in conventional energy production and hot fusion, they have been unable to follow the conventional path of technological innovation and have been mostly met with accusations of fraud. They noticed that no conceivable demonstration would be good enough for pseudoskeptics, so they focus on commercialization, which is the only way to get the devices accepted. -- Berke Durak

