I should have been more precise with my terms, but there is a difference between "food" and the "food industry" indicated by the likes of Nestle. Yes, everybody needs food. No, nobody needs the ultraprocessed junk Nestle produces.
I didn't see the OP's point as whataboutism, but rather putting things into perspective. We are debating the water usage of a powerful new technology that a large fraction of the world is finding useful [1], which is a fraction of what other, much more frivolous (golf courses!) or even actively harmful (Nestle!) industries use.
[1] https://news.ycombinator.com/item?id=45794907 -- Recent thread with very rough numbers which could well be wrong, but the productivity impact is becoming detectable at a national level.
- food, a thing that literally every human needs every 24 hours (really 6-12) to continue to live
- GenAI, a new product with dubious value that contributes significantly to the systemic enshittification of the US and global economy?
FYI whataboutism is a well known (and honestly quite lazy) fallacy and propaganda strategy: https://en.wikipedia.org/wiki/Whataboutism