Most asian immigrants came here with nothing and much less resources than the caucasians who've already been here for years. They worked hard and performed well on the SATs and got into great schools and as a result are now generating a higher than average income than caucasians.
https://www.wikiwand.com/en/List_of_ethnic_groups_in_the_Uni...
Not trying to brag about asians here. It's really just part of the culture and it can get really extreme. It stems mostly from parenting... the memes below are really illustrative:
https://www.pinterest.com/lindaschloss/asian-father-memes/
I think one time when I was a kid I mentioned to my dad I was interested in becoming an artist. My dad beat the shit out of me. Now I'm on hacker news and I'm definitely not an artist.
I would argue that what is causing the income disparity is the ability to work hard and study. This ability leads to higher test scores and higher income.