Why does Holden give the nuns so much money?

Holden meets the nuns in a cafe and they start talking toeach other. The talk about school and books. Holden insists on paying for their food and then gave them ten dollars in their basket. Holden is so used to people being mean and fake, he meets these nuns and he realizes that they aren't fake and that they genuinely enjoy talking to him. Holden had thought that all the real people had left to be replaced by their falsely sweet masks. The nuns and their kindeness was real and he wanted to help them.