system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why does the USA subsidize the production of corn? 

Update: Holy hell, I appreciate all he feedback from everyone. Ive tried to read about his subject a few time but I seem to have a hard time retaining information from all the different sources. Thank you all very much.
gpt
1) In the 19th century, we found out through long and bitter experience that leaving farmers to the free market was a bad idea--the wild fluctuations of farm prices made it very hard for them to do business. And we liked family farms and thought their existence was important to our national well-being, independent of the food they produced. Down-home virtues and all that.

2) In the 1930s (the New Deal), the government stepped in to more or less run the market. It smoothed out the swings in prices and made it much easier for farmers to get by.

3) In the early 1970s, a bunch of factors combined to create shortages of some foods. Plus, inflation was making food in general more expensive.

4) The government changed its policies from smoothing out market swings to subsidizing maximum production.

5) These new policies favored BIG farmers, not the regular old family farms. "Get big or get out," said Earl Butz, Secretary of Agriculture. The family farm started dying and is now essentially dead.

6) Big farmers, like any other big organization, are bureaucratic, slow, and stupid. They weren't about to select the best crop for every acre. They could only plant one thing everywhere and call it a day. 

7) That one thing was often corn, which is better suited to big, dumb agriculture than other crops (except soybeans, which are also suitable). 

8) Because we had so much corn, we wound up finding new uses for it--corn syrup, cow feed that makes cows sick but who cares, ethanol, and whatever else. These uses were often subsidized because when a big corporation has a problem (in this case, corn they needed to sell) it becomes the government's problem.

9) So to review, the old-style farm supports had become subsidies for big agribusiness, and big agribusiness is too useless to do anything but the simplest thing--plant corn everywhere. (It also sterilizes the soil with herbicides and pesticides, then fertilizes it so the corn will grow. This is not a good idea in any larger sense, but it does simplify things).