It is the external security threats that necessitate the need for nation states, governments and militaries.
I disagree because I think distributed, decentralized individuals taking responsibility for their own security are very, very difficult to take over even by the most well-funded technically excellent nation stat armies (see Afghanistan). In my opinion, this "you need us" narrative is pushed by the nation state to keep people in fear. Having a standing army puts the people at more risk, not less. Nations want to take over other nations because of the tax-farming opportunity which is enforceable by the violence of the state. If the people reject that, there is no opportunity to extract from them as they will fight the very concept.
I don't think 1 is accurate. See examples like Detroit Threat Management (now known as https://www.threatmanagementcenter.com/ ).
As for 2, your argument sounds like "We can't have freedom because some day over time it might turn into government." That's a silly argument, to me. I think tribal and gang wars would be less effective if there wasn't a monopoly on "keeping the peace" (which does nothing of the sort). Police respond to crime, they don't prevent. Private, distributed security guards, for example, actually prevent crime before it happens. That's a much better model.
I do think there are alternatives. Many alternatives. I hope humanity evolves its consciousness to consider them. I suggest giving The Most Dangerous Superstition a read. More thoughts here, if interested: https://peakd.com/anarchy/@lukestokes/the-myth-of-authority