WTF am I reading?
To put that another way: if we know that a quantum computer can be made to outperform a classical machine, we've got a bit more confidence that the research money isn't being wasted.
We DO know the former. If it turns out that for some as-yet-unknown reasons, the QC actually does NOT manage to follow the mathematical description of QM, that would be monster spectacular and open the road for re-evaluation. Shurely not a waste of money one way or the other.