It shows that the difference in efficiency of doing a custom ASIC at Youtube scale saves more money that what's required to design and manufacture their custom

It shows that the difference in efficiency of doing a custom ASIC at Youtube scale saves more money that what's required to design and manufacture their custom chip. But this is different from the trend cost per transistor (particularly for smaller players!). And actually, this is the case because new processes efficiency gains are lower than in the past. It's something that's been said before (and I read about it on HN, it was just years back and I don't have the reference at hand now ;), but when process improvements were fast making a custom ASIC didn't really make sense: by the time the ASIC was designed and debugged and deployed, a few years were spent and a recent CPU was nearly as good as the custom ASIC for no risk and less effort. Doing an ASIC is hard and takes time, and having a slower pace of improvement for new nodes efficiency makes it easier to justify the long deployment. There is now time to use such an ASIC with a noticeable gain, and absorb the cost and gain. Still, this is for a Youtube or Google (TPU) or Amazon (Graviton) or Apple. You need this scale still to absorb the development cost.