There are some substantial variations within groups, too. Jewish people tend to have high incomes (but you won’t see that in census data, because the census bureau does not recognize “Jewish” as a distinct ancestry). People of Russian ancestry have twice the per capita income of all Americans.
The apparent higher Asian median household income is an artifact of Asians’ higher household sizes (as of last census, 3.27 people/household vs. 2.67 for all Americans), and partly a consequence of the fact that there are much fewer Asians over 70 in this country. In terms of per capita income, Filipinos, Vietnamese and Koreans are actually below average, but numbers are pulled up by the Indians and the Japanese.