system
Given the following post, respond as if you're commenting on Reddit:
human
Butter is a dairy product. Why, then, can butter be unrefrigerated but milk or cream goes rancid so quickly?

My friend ate 2-day-old risotto on the stove. Why isn't he dying?
gpt
Water content has a lot to do with it. The ability of bacteria to degrade the butter is controlled by the amount of water present. It has to do with the activity (in the chemistry sense) of the water. The available water is bound to other molecules and not available to bacteria that need it the water to survive.

Water can also hydrolyze fats and proteins creating rancid flavors.

Also, a lot of the compounds that taste good are easily oxidized and the oxidized forms can taste bad. Like that old ass jar of olive oil in your cupboard...it tastes like crap because it has gone rancid. It smells bad, but not because of bacteria. Often food will smell bad, but the bad smells are not the result of pathogenic bacteria and will not necessarily make you sick.

I am a geologist, so this may be a little simple.