If you work as a volunteer or for an NGO, you should know that everyone always acts in every culture and in every society only to benefit. To think there would be people who do not act for the benefit would not only be naive, but also malicious, because whoever is not acting to the advantage (which means to the disadvantage) would be a bad person, because acting to the disadvantage is destructive. Therefore the question about the difference of people is a different one, namely what does the particular person see as an advantage, is it just something in the narrow bounds for himself or his family, or is his thinking for a larger frame, does he act for the benefit of his fellow men (and he might choose who his fellow men are) or even to the benefit of all societies.
If you want to change a society, it is no use trying to get other people to be selfless, that will never happen. What can create change in a society is to change the consciousness of the people, so that the people see other people prosper as an advantage, or to see the existence of nature as an advantage. Then the actions will also change accordingly. The values are what motivates us to do something, and the values are given by the culture (not only material values). So we actually have to act in designing the culture to make a difference, and that is not selfless acting, it's something that really all people should do more or less.
If you make an event that also changes the culture, but not according to the content of the event, but according to the action of making an event. Thus, it is logically clear why our actions can never influence culture directly in a way we have planned, we are always affecting culture indirectly, through our every day actions. Of course, it changes more when more people see it, but for the ones who only see it through the media, it is of course altered in a way which is quite different than for the ones who see it in their own lives. Through the media, it has become something quite different in the impact of influencing cultural.
And if someone wants to help the development of another culture in another country or another society in his own country, then he should not try to see what would be of advantage for the others out of his own values of his own culture, otherwise the help will not work, and the project built will disappear as soon as the person who created it is no longer there, and no one will care about the material given. Because if it does not bring an advantage in the local peoples view, it will be regarded as worthless and useless.