If they scale up, buy out other farmers, basically go corporate, they can be rich. It also feels like there are huge regional differences (eg a California walnut farmer is going to be a lot richer than an Illinois corn farmer).
It’s bound to happen eventually, but we probably haven’t crossed that threshold yet.
Grain farming doesn't become a full time job until you reach over 1000 acres, if a guy farms one section of land and makes a decent living and chooses to spend that extra time enjoying life, more power to 'em, but farming in that 640-1280 acre pocket scales really well - it is a choice!
The over half of farmers in Iowa, most of which are row-crop farmers, that are running farms under 640 acres, are they dropping out because of economic pressure? Maybe some, but I think mostly it is old-timers that had a great run but they have a business that provides half an income to the next generation at the current scale and the next generation would rather do one thing than two. Either way, Dad's not retiring "poor"!
(This happens a lot in my neck of the woods, lots of 1,000 acre-ish farmers retiring with kids that are professionals that "love the farm" but have no interest in it at this scale.)