Shares of quantum computing company Rigetti Computing (NASDAQ: RGTI) were up a mind-blowing 400.3% during December, according to data provided by S&P Global Market Intelligence. Then on Dec. 9, Alphabet's Google announced a quantum breakthrough that exhilarated the investing community about the potential of quantum computing generally.

Rigetti stock is up 1,756% in the last year — but 74% overvalued. Investors who did not buy Nvidia stock before GenAI wave, fear missing out on quantum computing.

The shares of IonQ Inc. and other companies linked to quantum computing tumbled in extended trading on Tuesday after Nvidia Corp. Chief Executive Officer Jensen Huang said “very useful” quantum computers are likely decades away.

Quantum computing stocks dropped Wednesday after Nvidia CEO Jensen Huang declared that useful quantum computers are likely decades in the future.

CEO Jensen Huang lit the entire quantum computing sector on fire last night after saying the technology won't be "very useful" for at least 15 years and maybe as many as 30 years. He may as well have poured gasoline on the industry and thrown in a lit match.

Nvidia (NVDA) chief executive Jensen Huang doesn’t think useful quantum computers will be here anytime soon — and stocks are not reacting well to it.

The long wait outlined by Huang for "very useful quantum computers" throws cold water on a sector that was already expected to spend millions more on the technology, which can only perform niche calculations so far.