I guess that either both the police did very well their jobs (after the fact) and/or the 'insurgents' (almost) only had their guns as symbols and/or there was a lot of luck involved.
As riot raged at Capitol, Trump tried to call senators to overturn election
https://edition.cnn.com/2021/01/08/politics/mike-lee-tommy-t...
-Otto von Bismark
I keep returning to that quote in these days at it's so apt even hundreds of years later. The Capitol insurrection could have been sooo much worse. Only a handful of deaths resulted. That's incredulous for such an event. That a fire-bug didn't get in there and light the whole place up is incredible. That all of Congress was evacuated safely and stayed safe despite seditionists actively trying to lynch them, is amazing in the true sense of the word. The damage to the building itself was minimal, the art and statues are mostly intact, just unbelievable stuff. That despite saying he was going with them, Donny stayed at the WH and just watched the TV. Literally every other autocrat in history would have gone down to the floor of the House and declared themselves King. I cannot think of any other example where the tyrant did not do this (Sulla, but not really even then).
The US got so incredibly lucky in this that Bismark's quote is the only thing that makes sense to me.
Not to mention those that will result from COVID branching out from this event. Which - while less related - when considering the actions of the instigator are certainly notable.
DC has a ton of security, and it's basically only legal for them to possess the guns. Carrying guns openly in this area would lead to a quick arrest.
So - I think you're right that there was a lot of luck, but also there was a lot of preparation.
... only one of which involved a firearm, and that one was in the hands of a Capitol Police officer.
Also, there's still no explanation as to why there wasn't a large, anti-riot police force defending the Capitol that day…