Oml, I use to dye my hair all the time. Like from age 9 to age 17. I would change it every few months to a completely different color, meaning I had to bleach and then dye every time. I think I have had every color possible, and I use to do whack combos of them too. If I could go back, I would have never dyed it at all.
I never had anything super bad happen, HOWEVER, I use to have a very nice curl pattern when I was younger, but after all the bleaching and dying, my pattern is a lot more straight and that was not worth it. I hated curly hair when I was a kid, so didn't pay attention to my hair getting straighter, but as an adult it sucks. I miss having curls. Now it's waves that just look unkept...