Yes, I agree.
As an outsider, I would say that US democracy and institutions are easily strong and resilient enough to handle this level of insurrection and violence, or even ten times more.
The decisive fact is that the military, the FBI, the security services, the judiciary, and the police are NOT on the side of these people, despite a few rogue individuals. Neither is Congress, despite a few rogue Congressmen. Neither is any state government or institution. Neither is any large corporation or business interest.
The alt-right has no coherent organization, no capable leadership, no detailed plans, no significant financing, and no access to serious weapons. They are spread thinly throughout the country, among a population largely unsupportive of their violence, with no strong regional base to work from.
All of this means that they can never succeed beyond creating a few minor local disruptions. I know this may not look minor now, but in the larger scheme of things, this level of violence is minor and can’t achieve anything.
Your institutions and systems are strong and working. This incident is serving as wakeup call to deal with the problems that gave rise to the whole situation.
You will point out that nearly half of Americans voted for Trump. That’s deeply concerning, but it won’t translate into any kind of violent takeover of government, for the reasons I’ve given.
There are serious long-term problems that need to be dealt with, particularly the spread of false information and conspiracy theories through social media and mainstream media.
There are also serious economic and social problems that underlie the whole situation, and need to be addressed. The wealthiest country in the world has the worst health care system of any developed country, the worst social support network, the worst employment and environmental laws, and the greatest inequality.
But… violent takeover of the government is not going to happen.