Unlimited freedom is like unlimited power, too much power brings out the worst in people (especially the fear of losing it).
Freedom should have boundaries, it should end where one is violating another person's freedom. When you own a gun, you don't hamper my freedom to move. When you shoot me, you do, that's crossing the line.
When somebody breaks into your house, he's violating your freedom, your peace of mind in your own home.
Owning weapons of mass destruction is an attack by itself on the freedom of others, by sheer threat. No one should have those, not even states.
Some view owning a gun as a sheer threat as well. I'm not sure why they are wrong. Guns are designed to be very effective offensive killing machines. That's threatening. Knowing we could be killed at any moment while out at a public event brings with it some level of psychological harm. If everyone had defensive weapons only, that harm wouldn't be there and our well-being would go up.
They are a threat. Cops pull them out and point them at regular people all the time too. They do what we cannot do. If we did that, it would be considered brandishing at the least. There's a double standard though, and they benefit from it and special protections. No thanks!
I agree that governments should not own WMD's. Individuals would pay a heavy price for owning them too. What insurance agent would insure such a person? None would.