Due to the nature of averages, we can deduce that half the population is of below average intelligence. Even though driving on the freeway may inspire us to say most are in fact below average.
By the same token, half would be above average. If we look at the statistics we find that much more than half of the people are not rich. Therefore, many of the poor are of above average intelligence.
It's true that people who lack the experience of associating with a broader cross section of society, usually feel that the one they belong to is superior to the others. Each group finds a way to say they are better than the other groups. Some may say they are smarter, some more honest, some better workers etc. The fact of the matter is, in each segment of society from the richest to the poorest, we will find the full spectrum of intelligence and moralality.