Human beings are social animals and we have developed a society for us to live in. One may see this society as a number of bricks stacked but each of them has a load to share and stability is to be provided in the whole structure. Even if one brick fails, the complete structure comes falling down just like the game of Jenga. Similarly, in our society, human beings have taken up different jobs and responsibilities in order to cooperate with each other in exchange for a materialistic thing called "Money".
What would happen if we ceased to cooperate? Society will fall drastically as if anarchy was introduced to them. Without cooperation, there would no longer be the sharing of jobs and responsibilities and we will go back to the age of troglodytes. The concept of money will become obsolete and the empire of rich will be the first one to fall.
As the saying goes, "the bigger you are, the harder it will be your fall". If people stop cooperating then huge companies and corporates will get shut down, all the luxuries that have been used by us may no longer be used to work as smoothly as before. Further, if cooperation between humans will stop then the immediate response will be havoc and chaos all around. The very society we are a part of will come for each one us to snatch anything and everything of value.
One can see that consensual cooperation is like a lease on the dark rampant brains of humans. Co-operating is hence very important to avoid going back to a harder age of hunting and fighting especially when we have already been addicted to this structure of society.
On a personal level, creativity may boom if humans cease to cooperate and work for themselves but on a bigger picture, this is a bad deal in exchange for all the chaos it will release in human society. Murder, rape, loot, theft and almost all the crimes will get a boom and will be done in the open as the police who agreed to "cooperate" in the first place would have stopped. It might be the case that the very policemen who swore to protect us, would be the one creating all this havoc. As cooperation stops, humans primarily will lose their jobs and titles that were given to them to serve us, to cooperate in this human civilized society would only remain for the name-sake.