That math and logic has a few major holes in it.
You've mixed the commodity price for the mill price. Farmers don't see the commodity price for their goods. Truckloads of corn at the mill max out at about 350 cents per bushel. The middle man makes the money, not the farmer.
That 350 cent price is prime. It always gets knocked down for mosture, contaminents, quality, etc. No one, I mean no one, ever gets what it's going for.
Supply and demand work against a farmer. When a farmer has a great crop, everyone has a great crop. So prices drop. That's why you will see farmers tilling a good crop back into the ground. The price is so low it costs more to take it to the mill than to just leave it to rot in the field. Prices are only high when everyone had a lousy year and produced nothing.
No farmer puts in 60 hour work weeks. You can't go that lazy.
That $100,000 isn't a subsidy, it was a grant or a cost share, and contained easement rights. Not that one can't make money with them, but you give up some of your farming for it. Some of my cousins are making good money selling their lower fields for wetland recovery projects. Builders destroy a wetland for development, but buy some land to be converted to wetlands at his farm. He's made good money at this.
I know one rich farmer. He is rich, no mistaking it. He also worked like a dog most of his life. I worked for him. 16-20 hour days 365 days a year. Took him decades, but he put together a special consortium of like minded farmers and ranchers. Convinced a whole bunch of wealthy people to preserve the large portion of Colorado and Wyoming that they owned. Sold it all essentially, making it an interesting rural preserve. He got rich not by farming, but by selling the romantic dream to others.