I don't have many vices, and caffeine is not the worst one to have. Tea and coffee are rank. I can force green tea down on a good day, but it's not the most uplifting energy boost, particularly if it's been hard to avoid gagging on it
I like the way my brain feels sharper, calmer and more focused, and it helps with physical fatigue on long/ intense runs. It helps get through PMT fog too.
I do not get on with artificial sweetners and water is not the answer to everything on every occasion. I ended up buying one last week because that was the only non-diet drink in the shop other than a 2l bottle of coke and I needed some easily digestable energy to do a running intervals session.
Drinking about 4 per week in an otherwise healthy, active and well nourished lifestyle is not something I lose sleep over. Literally. If I'm overtired, it calms me to be able to doze off.