Most people don't donate to an alma mater just to support financial aid for lower-income students, nor just because they want to establish their family as a leg

Most people don't donate to an alma mater just to support financial aid for lower-income students, nor just because they want to establish their family as a legacy; they donate in order to improve the institution and the quality of education, research, and inspiration it produces. It's a way of paying it forward, much the same philosophy as why people might go into education.