This particular account while loss making for them it is not by all that much.
A comparable Cloud Storage account on GCP with Coldline storage would be $320/month ($0.004 GB/month) or just $96/month for archival ($.0012/month).
The actual cost to Google is probably < $80/month for this 80TB ( most of the data is going to be in stored in a version of archival given the standard restrictions of 10TB on export.
80TB is also an heavy outlier, given the typical available bandwidth today and disk sizes commercially available for most users it will take a lot of dedicated investment of effort and time to upload this amount of data into the cloud.
Also Google's personal storage pricing is not competitive for pure storage, Backblaze is only $7/month for example. The higher price and value is derived from able to integrate into other Google products and provide storage for those like Gmail, Photos etc.