Some people dislike coffee due to the fact that it prevents them from falling asleep at night.
Some people think coffee tastes bitter even if they add a big amount of sugar. This could be due to their tongues having double the amount of bitter receptors, which is referred to as being a 'supertaster'.
Some people steer clear of coffee in fear that they become addicted to it and can't function normally during the day without it.
Good quality coffee that is bought from popular stores such as Starbucks are quite expensive. Some people don't like paying too much money on coffee, so they prefer not to drink it.
Coffee is known for causing bad smelling breath, which makes some people not like it. See also Why is coffee good for you
Some people experience an upset stomach after drinking coffee, which is why they prefer not to drink it.
Some people don't like drinking coffee, or anything that contains caffeine, as it stains the teeth and makes it more likely to have a yellow color.
There are some people who like to do the opposite of what is trendy so as to stand out and be distinctive, which may be why some people don't drink coffee and are proud of it. See also Why coffee makes you happy
Some people claim that they dislike coffee because they cannot stand the way it smells.