vested interest

1 :  an interest (such as a title to an estate) carrying a legal right of present or future enjoyment; specifically :  a right vested in an employee under a pension plan

2 :  a special concern or stake in maintaining or influencing a condition, arrangement, or action especially for selfish ends

3 :  one having a vested interest in something; specifically :  a group enjoying benefits from an existing economic or political privilege