That a farm has a periodic yield while this sounds like a one off thing

A movie-set must have certain features (full, even, ready for shooting on schedule) and there are millions of dollars on the line - you don’t just plant a field and hope it meets spec - I would think someone was making case it would be ready for filming. That that’s time and effort. The movie industry unions have livable - one might say exceptional - wages, even for someone just checking to make sure the corn field is maturing properly, much less planting and tending the crop.

An un-referenced medium article says he invested $100,000 in the corn field and he generated $162,000 in revenue, with no indication of the expenses of monitoring or harvesting. The best result would be $62k (compared to the $20,000,000 Nolan was paid for the film) in profit if the “investment “ included all of the miscellaneous expenses I mentioned above (as well as the lawyers cost for acquisition, travel and time spent finding the plot and securing all of the contracts for farming and harvest) and wasn’t absorbed in the “film budget”.