Out of principle

People argue over the small stuff because they think it "as a matter of principle". And out of fear of the repercussion, if they let the small stuff go. "If I give in a little now, then later I will have to give in much."

But what is the actual repercussion? Does it have material impact?

And on a case-by-case basis, what principle is "at stake"? Whose principle? Worldly principle or God's principle?

The focus ought not be on me.