Parents buy a house for their children because they love you and are responsible for you, but my brother has no such obligation. He was born a year or two before you. You are equal in status. You are the baby of your parents, not you, but your brother.
Brother can help you, that's mutual affection, and it makes sense not to help you. Maybe he doesn't have the strength, he has his future home as the pillar. As a younger brother, you should also worry about your own affairs.