Right - let's just scare little Willie, give him a slap on the wrist and send him home with Mom and Dad who probably haven't the slightest idea of what he was up to in the first place, much less how to keep him from doing it again. Won't he have a grand time laughing it up with his buddies over this one, and wondering how long before he can do it again.
I don't know anything about European law, but here in the States he's committed the equivalent of a Federal offense. No, I don't think he needs to be tossed away in prison to rot, what will that accomplish? Several years supervised service teaching underprivileged or learning disabled individuals basic computing skills, without compensation, would fit the bill for me. I'd probably also be up for removing Internet access from his home for the duration of his sentence. If he, Mom or Dad don't want to go along with it, then yes, incarceration commensurate with a financial crime of this degree is more than fair.
Just my 2 cents worth.