[NeroASERCH]

You are partially right, but you are thinking about it the wrong way, IMO.
If the state had targeted someone and was coming directly after him, specifically, and sent a SWAT team or a small army to hunt him down, then you are right. Having a few guns would not make much of a difference. He would end up dead or captured sooner or later.
But when applied to society as a whole, the outcome is different. If the population was well armed and willing to use force, then things like the pre-WWII secret police kidnapping Jews in the middle of the night in Germany would be a lot more difficult to pull off. It wouldn't just be hiding in your house hoping the police don't come for you and knowing that if they do then you won't be heard from again. The police would be vulnerable. Maybe they can kill or kidnap you if they are really determined, but they would also take casualties. They are no longer able to just decide to take somebody and do so with impunity. They are now risking their lives in order to do so, and that makes them think twice before going to someone's house and taking them. And in the case of something as widespread as my example, entire neighborhoods of potential victims could join together and attempt to defend each other. Instead of things being completely one sided where the government does whatever it wants and kidnaps and kills whoever it wants, there is a potential civil war where both sides have casualties, instead of just one. Civil war is never really a good thing, but as an alternative to the Holocaust, it kind of is. Additionally, just knowing that attempting something like that might start a civil war might be enough to prevent the government from even trying it in the first place.
Imagine, for a second, how it would go. It wouldn't just be shootouts in people's homes when the government came to take them away. The police would be prepared for that. It would also be things like police officers getting killed when standing in line to buy groceries. It wouldn't be safe for them to ever go out in public. They wouldn't know if the person they are standing next to is just a complete stranger or is some guy who's going to kill them the second they look away. People would look up their addresses, and the police and government officials wouldn't even be safe in their own homes.
In your scenario where it's one person vs. the government, you're right that it would be bad for that one person. When it's most of society vs. the government, though, things are different. If the government is so bad and the cause so good that the people are determined to fight, then having a well armed populace really can make a difference.