"No matter how many billions you spend, you're not going to make a Chevette go faster than the speed of light."
You're comparing something that most would say is theoretically impossible, to something that most agree is theoretically possible and has already been achieved on a very small scale(LLNL ignition, of course not at the efficiency tipping point yet).
"The problems are technical"
The problems facing a mission to the moon were also technical, but with extraordinary funding they were able to fast track it by dividing up all the technical problems they faced and tackling them individually.
Fusion has many technical problems that could be tackled independently in parallel. See "When will fusion power my house (or vehicle)?" in the previously linked article. It covers this pretty extensively.
"You can't point at funding as a problem for fusion."
I can and did. The facts provided in the link are pretty compelling.
"..can't point at funding.... The problems are ... economic."
You contradicted yourself.
"No amount of money will fix that."
You've never heard of this thing called "employment". You have a technical problem, you use money to employ experts in the field that you are having that problem, and they come up with a solution. If that solution requires labor and materials to implement, you then employ some more people.
No or little amount of funding means little meaningful progress. You have some independent researchers working here and there to produce some papers and try to get published, but at some point you've got to coordinate activities and get appropriate amount of effort applied to each technical problem in an organized way:
You can't call BS if your only supporting argument is BS.