Also, what does assimilate mean in an American context? It’s not like America really has a strong well defined culture in the first place, it’s been like ever since the country was founded.
Please be careful about making generalizations based on race - they're generally incorrect/unprovable and rarely provide any value to a conversation. You can rephrase this to be "I've seen more Indians do better..."
Doesn't explain the "why" though.
I do have some ideas about why, but it requires going into some sociological analysis. (note: I'm a minority so I speak from that experience).