Something that benefits all of humanity in one person's or organization's eye can still have severely terrible outcomes for sub-sections of humanity.
Those who lost their livelihoods and then died did not get those positive outcomes.
For instance, it's still very possible that humanity will eventually destroy itself with atomic bombs (getting more likely every day).
"Many were increasingly of the opinion that they’d all made a big mistake in coming down from the trees in the first place. And some said that even the trees had been a bad move, and that no one should ever have left the oceans"