Roughly $50 billion has been spent globally on fusion research since the 1950s with nothing material to show for the effort; at what point do you stop throwing good money after bad? This strikes me as the learning from these posts.
Given these scales I'm not really sure $50 billion is a lot of money for the entire world to spend on an energy R&D project. In fact, that number seems surprisingly low, do you have a source for it?
Your mention of cost justification is ignoring the bigger picture that our economic system is setup to benefit public companies like Intel, and not grand research endeavors.
As an exercise to the reader, imagine what organizations/companies would exist if the contemporary economic incentive structures were different.