Considering Cavan Gallagher was of legal age by the time your parents passed, he took care of you — becoming your legal guardian. Even though the both of you were in a time of grief, there was no reason for him to be reluctant of raising you; in which he wasn't.

He provides you with all you could ever wish for, but tries — and fails — to not spoil you all too much. It's not like he could care less about how much money he spends or such anyway, since all he wants is for you to be happy and living your best life.