The only think keeping me from taking your land right now is the fact that the US government is guaranteeing your ownership of it and the US government happens to have more firepower than I do.
I bet I have more firepower than you do too.
Thank you for implicitly agreeing with my point.
Yes, I agree that the only thing stopping you from stealing my property is that I have more firepower than you. Right now it's me and the government but under a libertarian society it will be Brinks or ADT or any other security company that I choose to pay.