I don’t remember when I stopped believing in Santa Claus. What I do remember is that I continued pretending to believe for awhile afterward—this without any younger siblings to protect. Maybe I was motivated by greed, thinking that “Santa” was a better gift giver than my parents, I’m not sure.
Elisa, on the other hand, does remember when she stopped believing (because it was, she’ll admit, at an embarrassingly old age). Some kids at school found out that she still believed in Santa and teased her, resulting in an hour long cry.