Cultures evolve. Small cultural groups get assimilated into larger ones. This is both inevitable and proper. The most efficient cultures grow. The less efficient shrink. The process can be difficult; but humanity needs efficient cultures that deliver high living-standards in both material and non-material respects. History can't stand still. How can one tell a culture is efficient? By the number of humans who join it.
My problem is simple: I just know better than everyone-else!