I have to agree with the non sympathy card here. At the age of 20 they did know what they are doing, they possibly didn't think of the consequences, but they knew it was wrong.
When I was that age a little younger probably, I used to hang out with a crowd, on a sort of part time bases (if that makes sense). These guys where known to the Gardai, infact I was told by a Garda, that I was known to them by association. The guys were rich kids and thought what they where doing was beyond the law, as their parents would protect them, they use to rival in the chases from the Garda (actually more observations by the Garda of their movements) and the risks they took, basically they where little boy racers out of their heads on drugs, and dealing in their local areas. They knew damn well what they where doing was wrong, they just never thought they would have consequences to deal with.
And do you know what, they didn't for a long time (their parents protect them) all of them got shipped off to the UK for college, two of them got busted in England for dealing, one died, two ended up in "St John of gods" for breakdowns, one went off to Africa as a volunteer (just for a more rounded view) I really don't know what happened to the others.
My point is all of this guys knew what they where doing was wrong, including me (I never dealt, but use to smoke and party with them on occasions) they really didn't care about the consequences (although they where fully aware of them) of what they where doing, they thought they where breaking the rules, and being different, all they where, where want tobe drug dealers, with rich Moms and Dads, racing around in their cars.
Thankfully as far as I know they never killed anyone, except within their friends (I actually feel bad about that as he was one of the youngest one within the group, and I hope I never did anything to encourage him (his death was due to a genetic weakness in his Brain, which over usage of E and LSD type products would have caused him a brain hemorrhage, I was out of the group 3 or 4 years when I heard of his death, but in fairness he was bigger "in" with the crowd than I was, and I don't think I could have changed that.
Anyway again my point is everyone of us knew what was happening was wrong, no one was naive, very stupid yes, young and foolish yes, choose to ignore consequence. Everyone within the group knew what they where doing though, and that was at the age of 18/17.
Edit I never dealed in drugs, I just know people who did and my above post (long winded as it is) is how I observed it. I hope it doesn't cause upset to people, I'm just trying to make a point through my personnel experiences. That even low level dealers know what they are doing.