How exactly do you imagine "reacting badly" to someone?
There are two basic ways to put down a person: a personal attack, or a coordinated group attack.
A personal attack is reasonable only if you think you win, and even then your personal benefits should outweigh the possible costs (which are always non-zero). In an ancient environment, the alpha male would beat the pretender badly, and any accidental damage to the alpha male would be just a necessary cost for maintaining his position.
In today's environment, we have laws. But we also have people who break the laws. You should not attack the person physically, because that is illegal; but if you attack the person verbally, there is always a chance that they will counterattack physically. (If you are in an environment where some kind of physicall attack is acceptable, still: you attack them with fists, they may counterattack with a knife.) So the risks of confrontation are high. You also have to care about signalling -- even if punishing people with harmful behavior brings a net gain, the fact that you decided to do the punishment, exposes you to a possible intra-group attack. Some people will have different models of reality: they will say that what you did was even worse than what the other person was doing.
The traditional choice for average people is a coordinated group attack. In a village, it is easy to coordinate. Just wait until the person leaves the room. Then carefully discuss your opinion (of them acting high-status while not being so) with your friends. If everyone agrees, you know you have a group support, and you know you didn't miss something that the others could have noticed. Next time the person comes, they will find themselves with a low status.
In a big town this mechanism breaks, because people are not meeting regularly in the same setting. Someone unknown comes, acts high-status, leaves, and you may never see them again, or never again in the presence of exactly the same people. So you can't coordinate a group attack. Also you have much less information about the person, than you would have in an ancient environment.
You would have to find a good strategy for "reacting badly" to socially agressive people and be sure that people around you share your definition and agree with your strategy. Otherwise you will be considered agressive, and people you personally know may start to avoid you.
The other day, someone did something I didn't expect. It was something many people have done before; something that I thought of as very normal, but that I in no way understood and had not predicted.
As I said, this had happened many time before, so I wrote it off as "me not understanding people" or "people are weird" for a second, like I usually do, before realizing that "bad at" really means "lacking basic knowledge", which I had never realized before.
And then I thought "I should ask someone who is different from me why people do that, and eventually someone will have an answer."
But many people will have many more questions like this. So, what have you observed people doing time and time again, but never understood? Or something that you only understood after a long time or asking someone about it?
And can Less Wrong tell us, not necessarily why (I for one can make up evolutionary psychology fairy tales all day if I want) but what conscious thought process occurs behind these events?