In previous companies I've seen AWS and Azure do the same for >$10k bills from small startups. 1x$10,000 invoice is no where near as much as a lifetime of hosting a unicorn startup. Most cloud providers will even give you $50k to $100k in credits for 1 year if you are a startup from a good incubator/investor. It gives you incentives to not to care about how much you're spending. By the 1 year mark you're probably making some money, raising another series, and attempting to dramatically scale up your business so now you don't have the time to clean up the tech debt you've created to lower costs. They are absolutely making a bunch of money this way.

That 72K is probably not anywhere near how cheap it was for google to provide the service.

I had an € 1.200 bill from Google once for using their reverse geolocation API for a month. I complained and got a canned response saying something like "Fine, here's your money back but next time you're paying". It probably helped that I had been on the free tier up until then and complained that I never got a warning that I had surpassed the free tier amount of API calls.

I'm not using the service anymore,

Cloud providers somehow turned a commodity business into a high margin business. The costs are way lower than you think. The other factor is that keeping customers means more profit than throwing them out, even if they have made a mistake.