My grandmother and this old guy I know can't drink any kind of soda. They have some kind of stage type kidney failure. My grandma used to drink Diet Pepsi every day all day until her doctor told her to stop. Now she's switched over to drinking sweet tea.
Generally speaking it is bad for you, however like anything else that's bad for you, if you drink it in moderation and are still staying hydrated then you should be fine. Most soda is full of sugar, of course you could opt to get diet and zero sugar versions but they still have artificial sweeteners in them. There's also caffeine in most sodas that you can get addicted to, but again there are caffeine free sodas too.
That's a common cause. I also have it in both ears. In my case it comes from spending 50 years standing in front of high powered guitar amplifiers and listening to playback though headphone at excessive volumes in recording studios. I can say from experience it's worse than cancer but I've learnt to live with it. I hope it's not too bad for you.
So is soda bad for you? As has already been said, anything in excess is likely to be harmful, even water but I personally have avoided soda in favor of water since I was a teenager.
What isn't bad for a person? Sure Soda isn't the best, I drink one can a day for that midday boost/pep and a different taste of drink. Maybe two or three on a weekend or special occasion day, but nowhere near the several cans a day, half to full liters that I see people drink daily.