What are the other options you would want to replace those proven technologies with? Sure, there are better semiconductor materials but they're expensive and already used where it makes economical sense. Nanotubes or graphene can't be handled at scale yet. Superconductors need huge contraptions for cooling. Using organic molecules is messy, see OLED. Optical parts might help, but that is difficult with silicon which brings us back to the other semiconductor options. Spintronics are already being put to use but those things have eye-watering prices.

Look at intel, even incremental changes can go wrong and cost you competitiveness.

Classic innovator's dilemma. I personally am biased to silicon optics after seeing a few impressive demos. Albeit in laboratory conditions, under controlled settings ;)

Rise of the learning machines

https://www.nature.com/articles/s41566-020-00748-w

That's not as much money as it sounds for the industry.

Apple revenue is more than that each month.

There's enough money around. So it seems unlikely that the cost of TSMC silicon fabs would be the obstacle to others developing alternative computing paradigms.

How is the "Cage of Birds" experiment going at TSMC?

Could you give some more search terms? Google isn’t returning anything.

Search for Nikkei article on TSMC and growth plans. Look for "cage" and "bird" search terms at that source.