The only company making AI chips, and allowed to buy from ASML, is TSMC, otherwise it's probably memory manufacturers.

Even if the order book is mostly TSMC, it doesn't necessarily mean the demand is mostly driven by AI (although maybe it is) - there are plenty of other high volume TSMC customers like Apple, AMD, Intel, Qualcomm, Broadcom ...

Finally, just because lots of TSMC customers may have made forward commitments (or whatever it takes for TSMC to commit to expansion), the main conclusion would seem to be that they needed to do that for business continuity given current capacity constraints. It's not clear why the need for them to do this should be taken as a sign that the AI datacenter bubble won't pop. Do you want to be Apple and gamble that rather then locking in TSMC capacity now you can gamble on the bubble popping and maybe get better terms later?

As a counterpoint to this "no need to worry" story, CoreWeave's 5 yr bonds are now yielding 15% ...