How did Betsy's brother prove to be quite selfish?

Betsy, Lyddie's roommate, uses most of her money to put her brother through college. Betsy's parents are dead, but she has an uncle in Maine who allows her to visit. When Betsy has time off work to go to her uncle's for a holiday, she doubts her brother will have time to see her. She fears he may be "too pressed with invitations from his university mates" to spend time with his sister, even though she is the reason he is able to attend the university. Later, when Betsy becomes seriously ill, Lyddie writes to her brother. Although he is less than a day away from Concord Corporation, he writes that he is too busy studying for final examinations but that he may be able to come at the end of the term to visit. Betsy laughs, but Millie is appalled at the brother's selfishness. Betsy asks if Lyddie wouldn't do the same to help her little brother, and Lyddie almost replies that Charlie is nice. She obviously means that Betsy's brother is not.