Be all things to all men/people
Definition 1 of 1
Pro Tip 1/3Cultural Nuance
This phrase is often used in contexts where someone is expected to adapt to different groups' expectations. 
As a teacher, she felt pressured to be all things to all men, tailoring lessons to each student's preference.
Pro Tip 2/3Emotional Undertone
The phrase suggests an impossible task and might imply frustration or a wish to do the impossible. 
He's burning out in his efforts to be all things to all men at work.
Pro Tip 3/3Impractical Expectation
Use this phrase to express that it's not realistic for someone to satisfy everyone's desires or needs. 
Our product can't be all things to all men; we need to target a specific audience.