Almost any reactor requires power to initiate itself. Jet engines don’t start themselves, nor does your car. This is no different; you put energy in, you start some reaction - and you get energy out. Hopefully you get a lot more out, than it took to start the reaction. Even a Dam required powerful electric motors to lift the flow gates to start the process. I can’t think of any energy device that starts itself without some energy input.
Even if this is a simple factory heater; that would be a heck of a device. If this does nothing other than heat water - that would reduce electrical demand substancially in the winter months for homes and factories. Steam turbines are neat; but if this can’t produce the volume of steam - if what heat it does generate is cheaper than other means, then this is still a good thing.
The first internal combustion engine was horribly inefficient and unreliable. It took several years, and thousands of engineers/scientists dedicating their lives to studying what was going on in that engine to get where we are today.
The onl thing that disturbs me about Rossi, is sloppiness. There is no excuse for sloppy data collection, especially at this stage of the operation.
Going back a further century and a half, the first external combustion engines were likewise.