Also from an economic standpoint, which I can talk about a bit, there is obvious rent seeking going on here. Thousands or tens of thousands of people have been tricked into studying in this field and have absolutely no viable product to show for it, so they lie and say its coming soon™. They are tricking people and government organizations with money into proving funding, every once in a while they have to set up a little tech demo to assure their patrons that significant progress is being made.

Its like fusion, its always 20-30 years away so that the players today can make their money and retire before anyone calls them on their bullshit. Lockheed martin claimed almost 10 years ago that they had a viable fusion reactor for small scale power generation, they did this in response to a failed experiment claiming to show viable fusion, they wanted to throw their name out there to get the investment, since then its been swept under the rug.