Anyway, just in 2019 the US DoE got a budget allocation of more than half a billion dollars ($564 MM to be precise, see [1] page 162). ITER's financial statements for 2019 ([2], page 43) shows member contributions of € 400 MM, which is again about half a billion dollars.
If we could manage to add up all the various research budgets for fusion, we would probably be quite a bit above the "never fusion" line, we could maybe reach the "moderate level" in the graph (the orange line).
But the question is: is this needed? MIT alone has a fusion project (SPARC [3]) that appears to be ahead of ITER. A spin-off of that project is the Commonwealth Fusion Systems [4], which managed to raise about $200 MM of funding entirely from private organizations.
Is it possible that we'll see a repeat of the Human Genome Project scenario, where the US Government invested $10 BN and more than a decade of reasearch, only to see a private company (Celera [5]) come in an steal the thunder at the finish line, with only a 20th of their budget?
My point is that as society progresses, there is a time when a certain thing becomes achievable on a medium budget, which only 50 years before would be impossible on an infinite budget. Just think about sending a rocket to the Moon in 1920 or creating an mRNA-based vaccine for the coronavirus in 1970. It is very, very likely that if the US government had allocated $50-100 BN for fusion research in 1970, we would not be any closer to fusion today. However, today, 50 years later, we are at a point where fusion appears achievable only based on private investments.
[1] https://www.energy.gov/sites/prod/files/2019/05/f62/fy-2020-...
[2] http://e.issuu.com/embed.html?d=2019_iter_annual_report&u=it...
[3] https://www.psfc.mit.edu/sparc
[4] https://en.wikipedia.org/wiki/Commonwealth_Fusion_Systems