Why do you put butter in your coffee?

the reason is to increase fat intake, mainly people use butter because it tastes nicer with coffee but it could be tallow or coconut (coconut also is very nice)

And coconut oil is extremely healthy! Can be heated up without being destroyed (unlike all other oils excluding red palm oil). What I often do is put coconut milk in my coffee, which has a similar effect, just less pronounced.

coconut and cacao fats are the two vegetable oils that aren't toxic bullshit, and both are easily extracted without excessive heat and solvents you might want to try cacao, its' high stearic acid content is superior and the smell is actually nicer against coffee

Cacao butter is very nice indeed. Cannot be heated up without damaging it, means it cannot be used for cooking, but excellent for putting it in your coffee or hot chocolate.