That is one factor, but another is total cost of ownership. At large scales something that's 1/2 the overall speed but 1/3rd the total cost is still a net win by a large margin. This is one of the reasons why every major hyperscaler is, to some extent, developing their own hardware e.g. Meta, who famously have an insane amount of Nvidia GPUs.

Of course this does not mean their models will necessarily be proportionally better, nor does it mean Google won't buy GPUs for other reasons (like providing them to customers on Google Cloud.)