Jensen Huang said demand will continue to be stronger than its supply providesGetty ImagesNvidia's Q3 revenue forecast was not good enough for Wall Street's raging bulls.Analysts quizzed CEO Jensen Huang on where the payback is going to come from huge AI spending.He said some customers who are buying Nvidia's AI infrastructure are making immediate returns.Everyone on Wall Street wants to know whether massive AI investments will really pay off.Nvidia CEO Jensen Huang tried his best during Wednesday's closely watched earnings call, but he couldn't expunge these doubts entirely.The company's third-quarter revenue forecast didn't help.