but you would basically have wasted all the resources spent to purchase the farm pre-apocalypse

Sure, but if you instead spend them on something "normal" like videogames you've probably also wasted them in an apocalypse scenario.

Sure, but the apocalypse scenario - and there have been uncountable apocalypse scenarios even in my lifetime, starting with 'The Jupiter Effect' - is also very unlikely to happen. Buying farmland you never use or enjoy, and which brings in no rent profit, is a waste if there is no apocalypse. While playing videogames brings a lot of enjoyment.

The premise of this piece is to be "rational". To do that you need some idea of the odds. If you think another Tunguska event is something to prepare for, then having a farm is probably no better than playing video games - I can't even guess which would be safer from a random 10+MT event, and playing games is more fun and safer than doing the extra drive back and forth to the farm or operating the farm.