Grown ups know that life is full of hard choices and that it's pretty damned rare that you get everything you want in any situation. We also tend to understand that there are many things that we cannot change or can only change a little, sometimes over a long period of time.
Choosing not to choose or "standing on principal" is often counter-productive.
Some principles ought to be inflexible. It's kind of the definition of a principle. I know what compromise is, and I know right from wrong. It's wrong to compromise on certain things. If growing up means forgetting that, then miss me with growing up.
What genocide in the world can I do anything about? My country does most of them, and I never support them. I've been protesting my whole life. I am always against genocide. That is a principle. Not one you seem to share, but to each their own I guess.
So in other words, you choose to be flexible with your principles because there's so much in the world you can't do much about. All you can do is chip away. You've chosen this particular battle for reasons, but not others. Conveniently ignoring the consequences of that choice.