Most people aren't violent He-men. Sh|t, most people aren't used to violence *at all.
These people didn't know each other. I'm pretty sure several of them thought 'shpild I intervene? If the others hhelp me, we'll have this guy, no problem.
But how do they know the others will help? They don't.
Big dude, used to violence. Comparatively small onlookers, none of them knowing if they'll get any assistance if they go in. And if statistics are anything to go on, most of them aren't used to violence at all.
Still, this case is pretty clear cut. Yet I don't blame the onlookers for being scared of the situation. Most non violent people would be.
Dying for a €5 pizza is stupid. Expecting everyone to mindread each other and, wordlessly, attack an attacker is not realistic.
Expecting others to have training in violence is presumptous.
There are other ways to prove your 'manhood' than by fighting off whoever you think is challenging it. If you need to do that to preserve your pride, your ego/pride is already pretty badly beaten up to begin with.
Always use your brain. Analyse, conclude, then act. Do not go to prettythangwhooping mode by default in any given situation.
Not going for violence isn't about being a ***** - I do some things that many macho men would be intimidated by. If you wanna show me you're not a *****, do something that potentially can hurt you pretty bad. Then get banged up doing it. Then continue doing it after you've healed up.