Wasn't the problem with Cold Fusion that it did NOT replicate, and thus got sullied with a bad reputation, so nobody wanted to touch it.
Then decades later, it's still kind of open question. Aren't there some studies still going on, more on the down-low since it has such a bad reputation. Kind of like the super-conductor, have to keep it quiet and make really sure before publishing.
Sabine did video on Cold Fusion that was pretty interesting. https://www.youtube.com/watch?v=ZbzcYQVrTxQ