An asset is a useful or valuable quality, person, or thing; an advantage or resource. It cannot only create wealth but preserve it. Human beings are assets as well.
When you possess skills that are valuable and useful to your work organization, it turns you into an asset.
Nobody likes losing anything valuable. In the same way, no organization would want to lose you if you are valuable. It may interest you to know that an organization can give a raise to a staff who is an asset just to keep them from leaving while others might not get the same response.
In addition, organizations look for assets while others go looking for jobs in organizations. Upgrade yourself to an asset and become much more useful.