I have seen people doing well externally but obnoxious. I have also seen people who were not doing well but are thoughtful and compassionate. Sometimes a kind word is all that one can offer another in distress. The least one can do is not to say anything nasty like that Christian preacher (what's his name?) who condemned the Haitians for the earthquake. He said that it was God punishing Haiti.
I think it's more dependent on upbringing than anything else. A household where rude behavior is tolerated is likely to produce rude children who become rude adults.
That is because, people confuse money and wealth. A lot of people with money are very impoverished. Money is often accumulated, which means it is not circulated. Money is meant to move. The niggardly individual is bound to be wrought with worries. People who are rude are also usually habitual offenders of the 7 deadly sins. Pride Lust Vanity Greed Sloth Envy Wrath If you think about almost every rude thing anyone has ever said to you originates from one of these failings. Caveat Emptor