system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: why does gas in the united states contain 10% ethanol?
gpt
It was supported by environmentalists under the belief that it could replace oil and be amazing for the environment. Farmers loved it because it created a huge demand for their corn products, and came with a bunch of subsidy money too.

Performance guys like it because you can put out more power in an engine with high ethanol content when the engine has been tuned for it.

Realistically, it has caused nightmares for older vehicles and most small engine devices like lawnmower because it damages components not designed to have it in the fuel.