I have no doubt that plasma fluid physicists will learn a great deal from trying to get ITER lit up. Just handed the money, they could have learned a thousand times more, and maybe even achieved practical D/H-3 fusion propulsion for spacecraft. But that will not happen at ITER.
And for comparison, look what the ISS has brought us commercially: We have a fully commercial manned spaceflight planned for next week. That is a massive achievement without even considering all the scientific work on the station.
All of the "scientific work on" ISS is done with crew literally pushing an "on" button on each bit of automated equipment running it. Experiments are forbidden to involve more interaction, and also forbidden to operate without that "on" button, so the crew has something, anything to do.
Commercial manned spaceflight could better have been worked without ISS. ISS's role was nothing more than a place to take them. Plus, a huge money sink on its own. It will soon fall out of the sky, and with any luck not hurt anybody where it crashes down.
Why is this relevant?
The sole fact that such a scientific undertaking can be done internationally, over decades, is a great thing considering the global problems we face.
Yes, ITER doesn't follow the USA economic ideology of "much", "cheap", and "now", but the world doesn't consist only of the USA and not everything works well with that ideology.
ITER is not a PV or battery factory. It is more like the ISS.