For avoidance of doubt my point is in no way a criticism of mankind:

• A % are always assholes.
• Also a % are always genuinely good people.
• The bulk of people are in the middle and kinda go with the cultural zeitgeist.

As far as I can tell, there are no more of the first kind than the second, though it's my impression that the third kind, in the middle, are at times in average more pro-social or more anti-social depending on the predominant culture of a place and time.

In the current Greed Is Good environment dominant in the West I would say that the bulk of people who aren't internally driven towards being a good person or being a selfish asshole tend toward "What's in it for me" anti-social behavior if only because that attracts more rewards and less social pushback, though as I said and in my experience of living in a couple of countries, local culture also has a big say in that.