I think there's a bit of a difference between preventing a run on the banks and propping up the entire stock market for the sake of just a handful of companies that all have big enough pockets to fail.

Well they sell graphics cards now so yes. Why would they suddenly not be okay with selling graphics cards if the AI bubble popped?

Their profitability would shrink, but they'd only be in trouble if they were taking on debt to expand operations on the expectation of future growth. AFAIK one of the annoyances gamers have had with Nvidia is that after crypto and now with AI, they've generally been very careful to control how they expand production since they seem quite aware the party could stop any time. It certainly helps to have a lot of product lock-in - people will bear much higher prices to stay with Nvidia at this point (due to, as noted - CUDA).

Sure, the stock price wouldn't be to the moon anymore, but that doesn't materially effect operations if they're still moving product - and gaming isn't going anywhere.

The stock price of a company can crash without it materially effecting the company in anyway...provided the company isn't taking on expansion operations on the basis of that continued growth. Historically, Nvidia have avoided this.

Companies like Nvidia. Microsoft, Amazon and Google are going nowhere. Just their valuations will in my opinion take massive dip. Which then will have all sorts of other effects.

They are not going to zero, but they can lose lot from the current price.