The difference between a hearing aid and a cochlear implant is that a hearing aid amplifies the sounds. A cochlear implant sends the information through the cochlea to your brain.
The problem with a cochlear implant is that it will destroy the remaining hair cells inside your ear. So if a person with a hearing aid is able to carry on a conversation, talk on the phone and do anything they want to. Then they don't need a cochlear implant. Why destroy the remaining hair cells for something that isn't guaranteed to work when you're already doing well with the hearing aid?
Once you get implanted, you won't understand everything instantly. It takes time and you will have to go for re-mappings and all sorts of adjustments once in a while. It's not logical to make a risk when your hearing aid is fulfilling the purposes it was designed for.
Not everybody is a good candidate.
