Mainly the pride, of course. You see, everyone at that party – EVERY single parent, knows how you feel. That there is even a cake on the table is seen as a tribute to your efforts. And only one person says, ‘Oh, it’s a UNICORN!’ before stifling giggles.
Your child is jubilant because, let’s face it, they don’t know what it could look like if a professional made it. They just see what they asked for, and that’s the best reward of all. That, and another slice of cake, of course.