A large majority of cloud users (businesses and individuals) think that the service provider is the sole party responsible for security. However, this is not the case.
The service provider must indeed create a secure environment for users and make sure all its defense systems are up-to-date and running, but users also bear some responsibility. Plus, when running computers and resources in AWS, which is a rather complex cloud environment, you need to step up your security game if you want your data to be safe.