There was a war between kings and Avraham got involved in it. What was his interest? It certainly wasn’t political since these lands were not his and he had no interest in any territorial acquisition or financial gain. He was wealthy in his own merit. His mere interest was to rescue his nephew Lot who had been taken hostage.
The famous commentary Seforno says on the verse: VAYIKCHO ET LOT, “And they took Lot…” (Gen. 14,12) the kings new that Avraham was extremely wealthy and he would not hesitate to pay the enormous redemption price they would demand. Avraham did not wait for any demands made by the kidnappers, though to him the money he would have to pay was no real problem.
Instead, he went to war. Why? Because he realized that if he would pay an exorbitant amount to redeem his nephew it would only encourage further kidnappings and even greater demand. It is important to do whatever is needed to save a life but the consequences of how we save must also be taken into consideration.