Huh. Now that you mention it, I was different when I was a kid as well. Difference is, I became MORE the daydreamer/quiet type.
When I was younger (6 or less)... let's just say I did things like squirt my mom in the face with a squirt gun and take a picture of her because I thought she looked funny when she was mad. Oh, and I also took advantage of an opportunity to runaway from daycare while the teacher was out of the room, even sidling under a security camera and crawling in front of a counter to avoid being detected. I apparently also took advantage of a low net on the outside wall of a playground in a bookstore to steal a book (didn't get caught, and they didn't believe it had been stolen when she tried to pay for it), though I don't remember it. My mom says I did it, though. I'd NEVER do anything like that now.
I basically went from being like that, to being like I am now. I think it was basically because I realized on some level, "Okay, planning stuff out ahead of time, thinking before you act... leads to good things happening. Taking advantage of an opportunity without knowing what you're getting yourself into... gets you in trouble and makes bad things happen." So I adopted the former approach over the latter. And I actually do prefer the way I am now.