A recent study from the California Institute of Technology (lay explanation here) seems to bear that out:
Fear really is contagious, and scientists say having more people around you for support won’t help. So much for “strength in numbers.” Researchers from the California Institute of Technology used a haunted house experience with 17 rooms containing various spooky threats during their experiment. They found people were actually more scared when the group walking through the house was larger. The team also found that their fear built up and increased as people moved from room to room. Scientists say when faced with fear, people are more likely to have a heightened physical response when other people are around. This “phasic effect” involves rapid changes the body experiences as it responds to an event and is more likely to happen when other people are dealing with the same thing.
I agree that most people lack the ability to historically or globally contextualize their situations - virtually everyone always thinks of the bigger home than theirs and not the mobile home down the street. However, I would offer we do ourselves no favors by going "Spinal Tap 11" on every issue. At least around politics and culture, every issue seems to be couched as a crisis and risks global thermonuclear war.
I agree with you that inequality matters, but I am not sure how much. I did a quick Brave search, and there are some interesting articles:
Europe and Americans - In Europe, inequality is a more significant driver of happiness, particularly among the poor and those on the left. In America, inequality's relation to happiness is more a function of being rich and less impactful among the poor.
Global Study - Not really sure how to digest the country rankings ... Uzbekistan ranked #1 feels odd.
Happiness is not a result of comparison
I'm probably wrong, but I think happiness ultimately is a function of looking inward than outward. Suicide rates seem to bear this out, assuming suicide rates are a measure of ultimate unhappiness. There is not a correlation between inequality or economics and rates of suicide ... I'm too tired to Brave it, but I IIRC it actually is the opposite: suicide rates tend to be higher among the wealthy.