I think laCster was just referring to the fact that maybe being younger he can't quite grasp the full consequences of his actions, and there's a good chance he won't be able to fully understand them until he's 23-25. I don't think that line had anything to do with the weed use. Maybe I'm wrong?
But yeah, stealing is wrong, especially something like a laptop, where you're not only taking an expensive piece of equipment, but you have access to peoples private messages, online logins, bank details and such. It's an invasion of privacy too and not very nice at all. Vandalism is just as bad, if you must, get good at graffiti and go spray some abandoned buildings or something, instead of egging houses, that's just petty and childish.