I think that tribalism is one of the biggest problems with humanity today, and that even small reductions of it could cause a massive boost to well-being.
Feelings of safety or threat seem to play a lot into feelings of tribalism: if you perceive that a group Y is out to get you and that they are a real threat to you, then you will react much more aggressively to any claims that might be read as supporting Y. Conversely, if you feel safe and secure, then you are much less likely to feel the need to attack others.
One implication might be that general mental health work, not only in the conventional sense of "healing disorders", but also the positive psychology-style mental health work that actively seeks to make people happy rather than just fine, could be even more valuable for society than we've previously thought. Curing depression etc. would be enormously valuable even by itself, but if we could figure out how to make people generally happier and resilient to negative events, then fewer things would threaten their well-being and they would perceive fewer things as being threats, reducing tribalism.