There's reason to think there's a bit more to it than just money. As the small plasmas people the startups (General Fusion, Tri-Alpha, Helion) are working with

There's reason to think there's a bit more to it than just money. As the small plasmas people the startups (General Fusion, Tri-Alpha, Helion) are working with now scale up there tend to be strange and difficult plasma instabilities that have a long history of rearing their heads. For instance, magnetic mirrors had the leakage out the ends which was fixed with a modification but that led to a show-stopping instability at practical powers. And the really big ITER-style things have scalability problems just from the sheer amount of superconducting magnets and materials they need.