Scott Aaronson calls it merely a “staggeringly hard” engineering problem, rather than something requiring new fundamental physics discoveries. To put it another way, with quantum we are in the equivalent of nuclear fission in 1939 – known to be possible with no theoretical roadblocks remaining, but still requiring an enormous engineering lift

Ok fair enough, but warp drive, Dyson spheres, and information teleporters are also "theoretically possible" with "known physics" and only requires a "staggeringly hard" engineering problems

A more realistic counter example is fusion energy. How long has that been promised but we still don't have any commercially viable fusion reactors