Why did quantum computing stocks suddenly crash up to 50%?

Rigetti Computing, D-Wave, Quantum Computing, IonQ & other quantum computing-related stocks suddenly crashed up to 50% on Wednesday. The fall came as Nvidia CEO Jensen Huang remarked, "Useful quantum computers are many years away". "If you said 15 years for very useful quantum computers, that'd be early...30 would be late...If you say 20, many would believe it," Huang said.