No, I’m going to eat one last steak, look lovingly at my supply of bulk dried beans and rice, thank goodness for the enormous amount of shelf-stable food sitting in storage across the supply chain, and wait til somebody dusts off their plow and uses that vast quantity of good land that, in this counterfactual, has been left fallow for some reason…
Labor is far from the only input into agriculture. The US’ advantages in arable land acreage, agricultural technology, and chemical inputs seem sufficiently efficient that the US is (and long has been) a net exporter of agricultural commodities.
One guy in the air-conditioned cab of his fancy tractor hauling his 40-meter-wide planter or 186-liter-per-second combine [0] can do the work of hundreds of his manual-farmhand counterparts without even taking out his earbuds.
Do you imagine that you would start “killing people to boost your odds of survival”?
[0] https://www.deere.ca/en/products/planting-equipment/db120-48... and https://www.deere.com/en/harvesting/x-series-combines/
I would imagine people would go into your house + every warehouse, and just start looting everything. Most people do not have a large supply of non-perishable goods and will likely try to take yours.
My point is the "vast quantity of good land" the USA has would be useless in a short-term famine scenario. It takes months to grow food. If there's a scenario in which the USA has outsourced its entire food supply overseas, and that food supply is cut off, unless there's a 3-4 month stockpile of food for every person in America and the USA figures out how to restart its entire farming system in a week, people are dying en masse.
Even if that occurs, there's still going to be riots like COVID-style runs on toilet paper.
That's why food self-sufficiency is critical to national security.