"Far better to do good by misintention than to produce evil by good intention."

As I said, that's the way people justify terrorist bombing campaigns.

Whatever you do has numerous consequences, and the consequences have consequences and so on for ever. Working out the arithmetic to determine whether the good consequences out weigh the bad isn't something that can be done instantaneously; in fact I can't see how whether it can ever be possible to come up with any unambiguous answers about that kind of thing, especially if you try to allow for the other things that might have happened if you had acted differently.

It's all guesswork. And that is when, when arguing with other people of good will who come to different conclusions, it is absurd to lose your temper and throw insults and sneers. Or to respond to insults and sneers in like manner.