Assumptions: milkshakes are fungible (I can buy a functionally equivalent milkshake), I have the wealth to acquire a replacement milkshake without significantly shifting the balance of my assets.

Under those assumptions, you have deprived me of the exchange value of my milkshake at the time it becomes known to me that you have misappropriated it. This is my moral judgment, not a legal opinion.

[Edit: I did not take your response as a frank disagreement, and anyway, even if it were, there's nothing wrong about disagreeing with me. I'm not an ethicist, just an opinionated rando.]