I think this is the most important line. Even if these companies are overvalued, I don't think there will be a nasty pop (this could change if banks start getting more involved, but so far it's been mainly company reserves and VC funding).
except that this doesn't quite add up IMHO
1. we have the current _speculation_ on an explosive need of both more data centers and energy if AI has a break through. This investments are mostly not from the big tech but VC/higher risk investment soured.
2. VC isn't always just private equity, I have seen enough rent founds, banks and similar acting as VC investors. Sure mostly by proxy, but they are doing that anyway.
3. 1st point also involves a lot of loans handled and resold by banks...
4. even with out all this a lot of founds are based on S&P 100 and similar. If the AI bubble goes pop before it's filled with enough magnetizable value a lot of the companies in there will lose a non negligible amount of valuation, which will have shock waves across much more then just "big companies".