Couldn't disagree more, fighting tyranny is absolutely a legitimate reason to own a gun. Consider the case of Breonna Taylor who was wrongfully killed in a no knock raid. Her boyfriend got into a shoot out with the police as a result, if he wasn't armed he could very well have been killed himself. That's not the only case of a citizen defending themselves in a no knock raid and probably not the last. Or consider the open carry protests when compared to the protests that don't, notice which tend to find themselves on the receiving end of some rubber bullets and tear gas. I don't think that's an accident.
I really find it odd that leftists scoff at the idea of defending oneself from government tyranny as if its some wild hypothetical scenario and not something that has played out over and over again in American history. The problem is when people say "government tyranny" they usually imagine some totalitarian government sending tank columns through the streets of America. But more often than not government tyranny in America has been at the local or state level. I mean if Jim Crow isn't government tyranny then I don't know what is. I'm not saying guns are the best form of resistence to that kind of tyranny, it wasn't an armed insurgency that ended Jim Crow after all. But on an individual level having a gun can mean the difference between being tried by 12 or buried by 6.