Yes, quantum computers are good physics research in the same way that ITER can be considered good plasma research. Neither will produce a working product that some people are expecting. I'm not sure that QC will discover the problem before we infer it theoretically due to the many engineering challenges, but it's possible. If any real progress is made in QC, my bet's on boson sampling.

Yeah, seems very win-win. Either we get a working quantum computer or we make revolutionary new discoveries in physics. Either option would be pretty exciting.