The F-35 is certainly a troubled weapon system and was, arguably, a bad idea (to suit 3 services) from the start. However, calling it a ‘national disaster’ is a bit of a stretch. Every big weapon system has its growing pains and developmental issues. The F-35’s issues may be toward the upper end of that curve, but they’re not unprecedented. Ultimately, most of the outstanding issues will be resolved and the services will get an expensive weapon system that performs “ok” but not great. That’s not good, but it’s not a disaster.
Perhaps there’s merit to acquiring a few less F-35s and, instead, procuring a few more F-18s, F-16s, etc. But, at this point, killing the program altogether would probably be more costly than seeing it through because you’d have to start ANOTHER weapon system and fight through all the same kinds of issues.