It can be profitable at times. Right now, last year was a banner year for hay, so prices are down a bit. 4-8 bucks a small square bale vs the 7-10 of 2019/2020.That would explain what I would see growing up in N Jersey - it was mostly dairy cows and growing hay is or was very common, especially for smaller landholders.
but figure you can get 100 bales per acre average, and 10 acres, times 3 maybe 4 cuttings a year and you’re looking at 12-16 k minimum off hay. It’s good for areas that flood a lot or stay wet long into the planting season.