New features and minimum number of users.

Sometimes it happens that the owner of the product says that he wants a new function added to our information system and that he wants it because our users want it. But the real situation is that 1 or maybe 2 users have expressed their desire to the owner and now extends it to all users.

Because each functionality or additional change adds complexity, it should not be done in a 1-2 user request if there are more than 10,000 users.

My question is, is there a good guideline on how many of the users should be positively affected by the change, so that it "pays"? In case this situation occurs, I can say, for example, "we must evaluate your request and if around 20% of our users are interested, we should do it".

I'm not talking about fixing mistakes or financial profitability.