I agree with you but it also makes me think: Google's TPUs are also fixed costs and these research experiments could have been run at times when production serving need isn't as high.
There is plenty of people who want cheap compute and are willing to wait till 3am if that's when the cheap compute is. Happens for all computing services, but for ML stuff the effect is even more pronounced because compute costs are typically a large part of the cost of many projects.
