VIRTUOUS WAR OR WAR FOR VIRTUE

It is like asking do you do business for the sake of it or to make profit out of it?
The war of Kuruksetra was not fought with virtue at the centre, but was fought to establish a virtuous kingdom in the future.
When Dharma fights Adharma, on the practical front adharma uses all tactics to win- dharma adharma  and whatever it takes to win. Therefore Adharma is very powerful and enterprising.  But Dharma on the  other hand is constrained by its very rule and has less avenues to win.  When Dharma fights  a virtuous war against Adharma it has hardly any chance of winning.

Lord Krishna decided to play a new game for the pandavas, who were virtuous but losing to adharma.
They were made to change their vision and strategy .
Krishna made them fight the adharmik kaurvas by all means virtue or no virtue,  to establish a virtuous kingdom.

For a dharmik person to give up dharma is adharmik, and in practicing the virtue of dharma he or she finds inner satisfaction .The dharmik or virtuous people are willing to die but not give up  their dharma.
But Krishna taught them a new lesson  "give up dharma for some time to establish dharma for a long time for a large number of people."
Of course it is not that the dharmik person gives up dharma altogether because he loses patience or that he starts believing -“it is not profitable and easy to practice dharma, therefore better to be part of the crowd and follow adharma.”
Most people follow the above trend.  However Krishna was not teaching hopelessness in the course  of practicing dharma, but rather use of tact to establish dharma.

In the Gita  he said to Arjuna  “amongst the gambler I am the greatest cheat.”
This does not mean that krishna is a habitual cheat,  but  rather  he says he uses cheating  against the habitual cheat to end their legacy .This  facilitates establishing the life of transparent relationships  or dharma  where people do not fear being honest and straight.

The reality is that after the war neither Krishna went  around cheating nor were the pandavas  addicted to cheating. They ruled with dharma at the centre and made most  people happy in their area of influence.