If "this experiment" is trying to build a machine, then failure doesn't give much evidence against the theory. Most machine-building failures are caused by insufficient hardware/engineering.
In the specific spot I commented, I guess you were just talking about the physics part? But the GP was talking about both physics and physical realization, so I thought you were also talking about the combination too.
Yes we can probably test the quantum theory. But verifying the physics isn't what this comment chain is really about. It's about working machines. With enough reliable qubits to do useful work.
On the engineering end, the question on if a large-scale quantum computer can be built is leaning to be "yes" so far. DARPA QBI https://www.darpa.mil/research/programs/quantum-benchmarking... was made to answer this question and 11 teams have made it to Stage B. Of course, only people who believe DARPA will trust this evidence, but that's all I have to go on.
On the application front, the jury is still out for applications that are not related to simulation or cryptography: https://arxiv.org/abs/2511.09124