Benefits are why we undertake projects. Whether it's for cost savings, achievement of a compliance standard, or protection of reputation, each provides a tangible or intangible benefit of a quantitative and/or qualitative nature.
If the benefit exceeds the cost, and the benefit exceeds the benefits of other competing initiatives, a project generally proceeds.
Benefits are elaborated in a business case, which should be written in the first stage of a project. During the course of a project, if the expected benefits may be compromised, it's a good practice to re-evaluate the attractiveness of the project to determine whether other initiatives may be more worthy of the change budget.