If it makes people feel better, Cecil was 13 Years old. Lions generally live to between 10 and 16 years in the wild and longer in zoos (where they are unlikely to be killed by younger, stronger lions or catch diseases). He had a good innings!
Also, the money that this guy paid for the kovod of killing an unsuspecting animal does go to conservation and as such it is not wasteful.
I do however find the whole thing abhorrent!