There is a large community of bird owners who actively discourage owning cockatoos, and after seeing some of their web pages and reading about the issues these birds can have in captivity, I'm inclined to agree with them.
Cockatoos are often given up to rescues and pet stores because they become too much for their owners to handle. Since they frequently do imprint or bond closely with their owners, this can be traumatic for the bird. There are horror stories of how these birds are mistreated, or self-mutilate for no apparent reason.
Some bird species are just better left in the wild, and in my opinion, cockatoos are one of those species.