I thought they broke even a few years ago. (As much energy was generated as was fed into the process.) Also I thought the problem continues to be magnetic containment. They still can’t maintain the field properly to keep the reaction going.
My knowledge of this is very old.
So is mine. You are probably right about containment. But breaking even is a long ways away from being able to build a commercially viable system.
But I'm pulling for them. They will get there someday and life on this planet will improve. Airplanes will still need oil. So will automobiles unless there is an order of magnitude improvement in battery technology. So will plastic factories. But give it a decade or two and enough capital and it will move a lot of our energy needs to electric. It will be a slow process. It will need the big breakthrough in battery technology. But it will happen.
I give it 50 to 100 years.