Why did darry feel hatred for paul holden?

In "The Outsiders" Darry feel hatred for Paul Holden because he did not became a Soc. The both of them were best buddies, they were best friends, but that ends when Paul decided not to be a Soc not because he want to, but because he needed to. He doesn't have enough money and also, he was orphaned at the very young age. His parents died when he was young.