Setting aside the fact that, if it actually works it would be clean, cheap, reliable, and nearly limitless energy for all, what about all the tech and science we're picking up just following this line of inquiry? Also, the entire budget stacks up pretty well against Social Security, Medicare, or Defense all of which are basically helping old people, poor people, or helping us kill people (kind of wasteful).

Finally, how is this research money zero sum? It's not like nuclear is completely broke or something because we're spending all this money of fusion.