If the people do better by cooperating, is it not in their self-interests to do so?
Only in retrospect.
Taking the Prisoners dilemma as an example, only when they act on behalf of their friend - the situation is for the better.
They won't know it was the best for them. Each of them will still think "If I confessed, I would be out in no-time, without the few months delay". But each of them acted according to the good of his fellow prisoner.
You could say the same would happen in a team-scientists scenario. A self-interest motivated scientist will think: If I work alone, it might take a bit longer to make the discovery/progress - but I will take all the credit/pride/money. That fits exactly for Randism. However, a collective-interest motivated scientist will think: I don't need the credit, nor the fame, nor the pride that it will be my discovery alone. As long as I keep donating to the team - the discovery will be made much quicker, and thus for the collective good of mankind - not for my good alone.
A scientist working alone would never make the discovery in his lifetime, in retrospect. A team scientists working together - would make it, and a lot quicker - than a chain of self-interest motivated scientists, each taking the former discoveries of the dead scientist trying to make it by himself - each dying before they make it.
Team effort is very significant in scientific research.
There is a very known test for elite intelligence units in the Israeli army. People are divided into groups, and positioned in a room with cards. They are told to try and build the highest card-tower possible. If everyone shares his ideas - and a brainstorm is created - it is far more likely the best idea will be chosen, or that the ideas will be mixed to create the most efficient tower-building way. However, if each participant thought his idea is the best - and he must prove so to the army oberservers in order to be applied - it is most likely he will not only fail - but the entire team will in arguments of who should do it, each participant saying "let me". Or worse, even if the participant does take over the team, builds it by himself while the entire team is paralized - the army will never take him. He doesn't cooperate, his excessive individualism paralizes his friends - he will never fit in a team working together towards a common goal.