IonQ's executive chairman said it's a bad idea to bet against Nvidia. IonQ stock rose a day after Nvidia's Quantum Day.

Investing is sometimes about weighing the potential reward versus the risks involved. Sure, IonQ could become a powerhouse in quantum computing. The issue is that the stock is already valued as if it's a given when it's not. If things don't work out as investors hope, the stock has an immense downside from its current price.

IonQ (IONQ) is one of the most high-profile names in the emerging quantum computing space, but not everyone is convinced about its long-term potential. Kerrisdale Capital, a well-known short-selling firm,