Grammar fix
a vested interest
personal stake (often hidden or self-serving)
a strong personal reason for wanting something to happen, especially because you will get an advantage or benefit from it, sometimes at the expense of others.
Hear it in context
Notice where the phrase sounds natural.
The committee members all have a vested interest in the outcome of the decision.
In my opinion, when politicians have a vested interest in certain industries, it can lead to biased decisions that do not benefit the public as a whole.
Fix the pattern
One small grammar move makes it sound right.
Not: He has a vested interest on the deal.
Say: He has a vested interest in the deal.
'A vested interest IN something', not 'on'.
Which sounds natural?
Tap the one a native speaker would say.
'Pecuniary interest' is legalese; 'a vested interest in' is the natural idiom.
Build natural chunks
Words that usually travel with it.
a vested interest in
- in
- have
- such
- those with