Good. You don't get to use my computer for a DDoS. I don't care why the DDoS was happening. I wasn't asked, and that's a serious breach of trust.
20 years ago during the P2P heyday this was assumed to come with the territory. Play with fire and you could get burned.
If you walk into a seedy brothel in the developing world, your first thought should be "I might get drugged and robbed here" and not what you're going to type in the Yelp review later about their lack of ethics.