Still four…always four

I took Sloan to the dentist yesterday to have his teeth cleaned. He walked right into her office and hopped up in the chair, informing her that he didn’t like the spicy toothpaste so could they please give him something sweeter.
“Will bubble gum do?” she asked.
“Oh sure!” Sloan said. “Go on ahead.”
Looking at me with an amused smile she asked Sloan, “How old are you?”
“Well, I’m just four,” Sloan said with exasperation. “I’m still four. I’m four everyday!”
“Are you ready to be five?” she asked.
“No,” he said. “I just want to be six.”
Why are they alwasy in a rush to grow up?