Once a Brahmin youth asked the great Brahman sage Vyasa: 'Sir, you say that a great war (Mahabharata Yudha) is going to be fought between the Kauravas and the Pandavas. Since you are sure of such a war taking place and war means large-scale devastation of lives and property, should you not use your clout and resources to stop it?' Vyasa narrated to the Brahmin boy a story whose gist was: 'I am helpless. It is beyond my ability and power to avert the war.'
I interpret the story in the following ways. First, the sage could genuinely not prevent the occurrence of the battle. This meant he was truthful in what he said to the boy. Second, Vyasa was an integral part of the conspiracy - the other two were Krishna and Yuddhishthira - that would make the war inevitable. Krishna was anti-establishment and anti-authority. War was a ploy for him to get rid of the bad and despotic elements in the empire such as Shakuni, Shishupala, Jarasanddha, Jayadrattha, Duryodhana, Dhritarashtra and others. Had these guys been killed by other means, Krishna, in all likelihood, would have gone down in history as a murderer, a criminal. So, this battle was invented by the three and was used as a natural cleaning tool. Third, had Krishna Dvaipayana Vyas stopped the war from occurring, his own reputation would have been in peril. He would have been called a great liar since his prediction that a great war will take place would have gone wrong. What would have been his status and the status of his famous father sage Parashara then?
Conclusions: 1)There was a very strong pro-war lobby; 2)The biggest beneficiary of Mahabharata war was Krishna who was systematically deified to Godhood and became an incarnation of Vishnu.