They’ve been conditioned not to resist since birth.
Individual heroics would just make you an easier target. They needed a bunch of them to execute a do-or-die charge so that a few of them would reach him. Hard to set up and coordinate while under fire. How many of us could set up a group charge against an armed target, know that most of you will be shot down before you reach him?
Setting up anything in this case is irrelevant. And yes, that's a question of upbringing what's natural to you - hiding or attack. You just run ahead and shout to encourage others. One hero can ignite a charge.
Probably not many of us. However, anyone with even a hint of a survival instinct could organize a group of folks to distract him (yelling, running, to get his attention on them) and then another group to spring when he's likely to have less chance of shooting (while reloading, or watching the others, or switching between weapons, as he apparently did here). There would certainly be casualties, but they would more than likely be lower.