Immigrants are also forced to develop their own peer communities and support networks since mainstream culture, stores, and media don't cater to them. Growing up I was surprised by how low the expectations were for my American classmates from their parents.

A "goof off" from my community would be struggling to get Bs while a goof from the non-immigrant groups would be struggling to pass at all. And being a "straight-A student" was a baseline expectation rather than a marker of being a rare and special talent. The bar for how many sacrifices parents are willing to make to set their kids up for success is higher too. I got a B- in Math ONCE and my parents immediately hired me a tutor and started forcing me to do remedial exam drills, which is a reaction I don't think I would have seen in the average or median American household among my peer group.

I don't think it's any special level of intelligence among the immigrant community, but I think there is sort of an "Overton window" of cultural expectations for what are normal ways to spend your time, what's an appropriate spread for grades to be at, or what things you should be prioritizing in life. I think immigrant communities maintain an Overton window that prioritizes scholastics over the mainstream culture.

This is probably in large part due to selection bias since the immigration process chooses the cream of the crop, but the durability of this tendency across generations is probably set up by the higher standards I talked about.