@Birdulon And if you don't buy optiso's argument that Will was delusional, then you could see the argument as "Your friends will die anyway, maybe by their own hands because your actions feel like a betrayal to them and to your ideals." and from that would follow "Trust your ideals, trust your friends, and work towards a shared happiness even if that means some of them might die. As long as everything is done with their free will and full understanding of the risks, then this must be fine."
(Then at the end Will does realize that he was being delusional when he thought he'd be able to handle everything on his own, but I agree that this was probably not what convinced him.)