You should take better care of your things. A leather case every 3 months is unbelievably wasteful. This type of careless behavior is killing our planet.
I appreciate that you rephrased this from your original comment, which was incredibly dismissive.
But this is still condescending and hyperbolic. I'm as surprised as the next guy that anyone would go through multiple iPhone cases per year, but I don't know anything about him, his family/habits/clumsiness, so I would not make such judgmental remarks.
And from a practical perspective, you will win zero converts by telling strangers on the internet that they are "killing our planet".