Coffee in excess can be bad for your health as it could lead to Insomnia, kidney disease, increase your cholesterol levels etc.
However in moderation coffee is actually good for you and can help protect your heart and may even prevent dementia.
People who drink some coffee everyday also have a lower risk of developing Alzheimer's disease, Type 2 Diabetes, lower risk of depression, lower risk of developing cirrhosis of the liver, lowers your risk of heart disease, strokes and even may even prevent Parkinson's Disease.
But too much coffee can be bad for your health but drinking 12 cups of coffee everyday is not gonna hurt you.
My Grandma lived to be 110 years old and she drank coffee for most of those years and she would drink 24 cups of coffee per day and she was very healthy.