You win some, you lose some.

[shadowscast]

So, you know the phrase "What you lose on the swings, you gain on the roundabouts?"

I know that its idiomatic meaning is that losses in one area are generally offset by gains in another. But I just looked up its more literal meaning (see this Quora thread) and I was terribly disappointed to learn that it's not actually about conservation of momentum, as I had always assumed that it was!