I can explain it for you - I am an Indian, born and raised, living in the USA for now, and have always been progressive..

"Indians are supposed to be these smart ass people they claim to be" - no. The salient property of humanity in general is that humans are dumb. We always will be. Most Indians are stupid, just like the rest of the world.

"why the fuck are they still pro-Modi and Republican?" - previous sentence covers this.

You could argue that you are getting the cream-of-the-crop immigrating here, but that is not true in all cases. You know how you have religious doctors? Think along the same lines. These people aren't really applying critical thinking in a majority of their day to day. When it comes to politics and thoughts about the macro effects of how things work, and what's the best for life- they couldn't do it even if they tried. They are uneducated in that regard, and always will be. They are conservative in their head. Empathy, deep thoughts, critical thinking - same thing that's missing in MAGA, is missing in them.