Coffee doesn't cause dehydration if you have enough water in it. While it can make you pee often, your body still absorbs as much fluid as required & expels the rest.
Roasting the coffee beans causes a loss of water
& mass, so the longer they are roasted, the less caffeine they have. Roasting gives them a rather chocolaty flavor.
There's no proof that coffee stunts growth.
In a study where girls aged 12-18 were tracked,
no difference in bone health was found between those who drink & didn't drink coffee.
Drinking coffee daily doesn't ruin your life as addictive drugs do. While there are no severe effects on withdrawal, one may have a mild headache or focus issues for some days..
Coffee doesn't cure hangovers. You may feel fresh since you will be ingesting water along, but it doesn't get alcohol out of your system. Instead,
it can actually worsen it.