A VESTED INTEREST

Meaning: when you have a vested interest in something, you have a strong personal interest in it because you expect to gain from it. This idiom is usually used in reference to people who use their power or influence unethically for their personal benefit.

In British English: if you have a vested interest in something, you have a very strong reason for acting in a particular way, for example to protect your money, power, or reputation.

For example:

• The Minister of Commerce is suspected of having vested interests in several companies that have won big government contracts recently.
• As both a shareholder in a publishing company and a published author, the newspaper’s book reviewer is seen as having vested interests in certain publishers.
• All the players of mafia game have a vested interest in keeping chaos in citizens’ minds.
• “They’re always highly dangerous because politicians, remember, have a vested interest in doom.” / Gash, Jonathan The Tartan Ringers
• “We all have a vested interest in its success, yet our politicians keep dragging it down.” / Sun, News of the World (2002)

You can practice this idiom soon at one of the English Mafia Club’s upcoming meetings: https://englishmafiaclub.com/events/upcoming-events