Rationalization is to find logical excuses for doing a certain act so that one can feel good about their decision or act.

When the locals make use of the coastal resources, they gain in terms of their livelihood. This makes them feel good about what they are doing even though they might know that they are actually harming the environment.

Restoring or protecting the resources will require funding that the locals do not have, and hence they find it hard to attempt at creating a sustainable management plan even if they understand the need to have one. So even if it is very obvious that the resources are deteriorating and they have to expand to other areas, they will rationalize that they are doing it for their livelihood because it is more important to them.