I suppose you might characterize the empathy deficit as the other side of that same coin. If so, then sure, that's a strong candidate to place at or near the very top of the pile. Unfortunately, the solution becomes even harder to discuss once you add said other side of that coin to the mix. How do you craft a sustainable substitute to literally feeling the pain of eight billion people, all at once, all the time, such that you genuinely care about what happens to them?

The other missing piece of the puzzle is an intellectual deficit. Humans are very bad at dealing with anything that's much bigger or much smaller than they are in part because they have trouble intellectually grasping it. That includes timespans that aren't even necessarily longer than a single human life. We also don't deal well with proper risk analysis for probabilistic harms on large scales, which may or may not be part of that same issue.

Provincialism in the broadest sense, then? Locality bias? Collectively, we have achieved so much that we've blown past our individual capabilities. Does that mean that, in some perverse sense, it was actually cooperation that killed us?