An idiom meaning that giving something valuable to someone who cannot appreciate it is pointless (casting pearls before swine).
彼に高いワインをプレゼントしても、興味がないから猫に小判だよ。
Even if you give him an expensive bottle of wine, he doesn't care, so it's like casting pearls before swine.
美術品の価値が分からない人に説明しても、猫に小判だ。
Explaining the value of art to someone who doesn't understand it is pointless.
そんなに親切にしても、態度が悪ければ猫に小判になるだけだ。
No matter how kind you are, if their attitude is bad it will just be wasted.
お金の使い道が分からない人に高級車の話をしても猫に小判だ。
Talking about luxury cars to someone who can't appreciate money's value is pointless.