expressions - Is there a saying or proverb for a situation where the weakest party will always lose?

Context - One might use it in the following situations:

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  "An employee has an argument with her boss and a dispute follows." (she gets fired a few weeks later)

  
  


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  "A student having an argument with his teacher over his grades takes the problem to the headmaster." (the headmaster doesn't want to get into it and says the teacher is right)

  
  


• "Workers go on strike for a week, get no raise and are considered absent from work."

You can say it to your son/daughter as a prediction: “Be careful mate, remember…(the saying)…

And you can also say it when he/she comes to you for comfort and support: “I told you, mate, they say that........(the saying).

Answer

The house always wins

is a proverb that comes out of gambling, where the house, the people running the gambling establishment, are setting up the rules so that they themselves are favored.