The bunker-building impulse demonstrates what’s wrong with libertarianism very well, an irrational attachment to individualism in all things. Libertarians refuse to acknowledge the positive role of nature and community in their lives, instead focusing on the negatives and spending all their energy fighting the very thing that keeps them alive. How long do you think you can last alone in a bunker without any support?
I also believe in autonomy, but everyone has relationships with people they did not choose to associate with due entirely to unavoidable circumstance. This doesn’t just apply to family, but to everyone on earth to varying degrees. You are just as dependent on community as you are dependent on nature, a complex web of relationships of which you are a small part. Refusing to acknowledge that these relationships exist because you did not choose to enter them is childish, and it enables you to behave selfishly because you do not take responsibility for your externalities. This is the same pitfall that capitalists dive into to justify pollution and all manner of horrible things.