I think this is a fair question.
I think the way they (my friends) approach it is that veganism is a personal choice. They understand how the food chain works and understand that some animals need to eat other animals. But they have taken a critical look at their personal role on the food chain and decided that for many, many varied reasons they don't want to put animal products in or on their body.
Also, the vegans I know that don't eat honey are also opposed to abortion, as a side, side note.
Hopefully some vegans will chime in here.