I have heard that "fusion is around the corner" thing was apparently because of some early assumptions about the core physics of fusion that turned out to be sp

I have heard that "fusion is around the corner" thing was apparently because of some early assumptions about the core physics of fusion that turned out to be spectacularly wrong. It turned out to be orders of magnitude harder. So that was one clear scientific reason. But people got the impression that the teams working on it are somehow unreliable, unorganized or keep moving the goal posts and are a butt of jokes. I think the messaging around it doesn't help. It's the same with batteries or renewable energy as well though.