Secondary Gain is a term known in psychology and the personal development field as the benefit that people get from NOT overcoming their problems. It is not known at a conscious level. The loss of holding onto a condition is far greater than the perceived gain. There is an emotional pay-off by staying where you are.
Secondary Gain keeps you stuck where you are.
Typically the word "gain" is a positive term. In this case it is negative. Secondary gain could be causing all kinds of problems in one's life. From weight gain, depression, to financial issues or relationship woes these issues never get cleared up or go away until the secondary gain issue is resolved.