for something like Oracle I really doubt that'll be the case. "too big to fail" for the huge US automakers and banks during the 2008 existential crisis was a real risk. If they did fall over then by all counts we would STILL be in a nasty recession not unlike what happened to Japan in the 90s. Which they still haven't recovered from. It would have been MILLIONS of people out of work for a VERY long time, and stuff like banks are crucial infrastructure for countries.
MS and Amazon are diversified enough where AI stuff not panning out won't really hit em too hard. might be a kick in the shin, not ripping its heart out. Oracle going whole hog on this AI garbage is a little too centralized of a business, but if they fall over then it won't really be that nasty.