In my case, not a single concert I worked ever, regardless of the act or the size of the crowd, required more than 50 security personnel, because you can generally expect crowds to behave in typical, predictable ways. I’m not revealing any trade secrets of crowd control when I say that not even the most extreme security plans call for a one-to-one ratio of police to protestors or security to attendees.
There’s not ever going to be enough police or security at any event to stop people if they all act in unison; if enough people want to get to Vanilla Ice at the same time, they’re going to get to Vanilla Ice. Social constructs and basic decency, not lightweight security gates, are what hold everyone except the outliers back in a typical crowd.
But the Capitol Police shouldn’t have been expecting a typical crowd; their reported plans, or lack thereof, indicate that they were expecting a pretty large percentage of this group to act with a basic respect for the rules and the minimal number of officers there to enforce them. But why?
Many members of the mob who marched on the Capitol clearly telegraphed their intentions in advance; some, terrifyingly, had even professed they were ready to die for the cause. Importantly, some professed this before they arrived. And yet, the Capitol Police appeared to plan for a mostly courteous crowd (and local law enforcement continues to say they had no idea what was openly being planned).