Quantum computing stocks were red-hot recently, but Jensen Huang just offered optimistic investors a reality check.

Microsoft dubs now the advent of a reliable quantum computing era. Quantum computing stocks are ripping higher on Wednesday morning.

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.