It’s likely not that this attitude results from his politics, but that his politics result from the same views that result in this attitude. It’s a narrow world view, perpetuated by propaganda and the american civil religion (not that this is exclusive to the US, but it sure seems prevalent there).

Ignore him best you can, and do what makes you happy. Not sure if there’s a way to convince him to help you save for it, but if he thinks that murica is the greatest country on earth, it seems unlikely he’d ever support you wanting to leave that - temporarily or permanently.