Woe to them! For they walked in the way of Cain and abandoned themselves for the sake of gain to Balaam's error and perished in Korah's rebellion.
Cain was a hater of his brother. He was jealous, but unwilling to do things God's way. Cain was a murderer.
Following Balaam meant to live a life of immorality. Many of the practices included unmentionable deeds. To follow those ways was to abandon oneself to those things.
Korah and his followers stood against Moses and Aaron. These false teachers are setting themselves up against the apostles.
These three examples are there to learn from. Setting yourself up against God and His way will never work out. The one thing that struck me about all three of these cases is that they are obviously wrong. I am speaking as an observer... to me the wrong way is clear and the right way is clear. but in the moment, I have no doubt that the ones who were going the wrong way believed that it was not the wrong way.