Hatvaarthakaamaamstu Guroonihaiva bhunjeeya bhogaanrudhirapradigdhaan ||
How could Arjuna ever think of fighting them and killing them in war? Arjuna and Pandavas might get a Big Kingdom and all its accompaniments like wealth and pleasures. But, Arjuna would always remember the killing of his Gurus and would never be able to enjoy the kingdom and its pleasures that he would get by killing them in the war.
yaaneva hatvaa jijeevishaamastevasthitaah pramukhe dhaartaraashtraah ||
We, the readers, will be wondering why Arjuna should be in so much confusion, dilemma and sorrow. He is one warrior, who is most prepared for this war.No one else has prepared himself for the war - as much he has.
After all, they were fighting for their just share of the kingdom.And, Duryodhana so arrogantly had told that he would not cede space equal to the sharp edge of a pin even, to the Pandavas.