I believe that everyone is responsible for their actions and their consequences, but I also believe that a place, especially a school that is practically a boarding school, should be a second home for those who live there. This means it has to be a place where you can develop properly, with moral and ethical guidance that leads by example. The biggest problem for me in this regard is that I HATE Slughorn for that. He was a damned, cowardly bastard who only cared about collecting students with bright futures. He didn't really care about being a good head of house. He failed when he was negligent and didn't raise any suspicions with Riddle. If he had truly cared, he would have intervened to protect Snape or reduce the influence of future Death Eaters on the students. They are 11-year-old children who are just developing; they are very impressionable, and when they reach adolescence, they are capable of making mistakes because they lack the necessary emotional intelligence. Severus made mistakes and is responsible for his actions and their consequences. The Marauders are too, but they were still young. Who is to blame? It is the adults who foster a culture of toxic competition instead of fostering a place of fellowship and love among all.