At 15% relative humidity, then, you can extract a maximum of 0.15 x 17.3g = 2.6g from every 1,000L of air.
If a person needs 5L/day for survival (I am making this up), then you’d need to dry out 5000 / 2.6 = 1,923L of air each day — that’s just short of two cubic meters…
If the density of people living in an area is 50 per square km, drying the air out to extract water would deplete the first meter of the atmosphere by 10%.
You made a unit conversion mistake there. It's 1923 cubic meters, not liters.
I was curious so I looked it up because I also did not know, ref: https://www.google.com/search?q=liters+in+cubic+meter&oq=lit...
Okay let’s say the bottom 10m of atmosphere is available for water making. That means there are 10 million cubic meters of air per square km, or per 50 people. We will need to dry out 1,923 x 50 = 96,150 cubic meters of air. But there is 10,000,000 available, meaning we are only drying out just under 1% of the air.
https://collaboration.cmc.ec.gc.ca/science/rpn/SEM/dossiers/...