"When you think you're safe is precisely when you're most vulnerable."- Kambei Shimada, Akira Kurosawa's The Seven Samurai
No win is ever permanent. With victory sometimes comes arrogance. That arrogance brings with it a sense of righteousness where we think that either the end of the battle is the end or that we are somehow invincible.
All warfare is based on some form of deception, misdirection or sleight of hand. Sometimes the win is just the calm before the storm or a rouse our opponents uses to gain the overall victory. In martial arts this type of technique is a sutemi-waza or sacrifice technique. We give up something small to get something even bigger.
There is a Japanese saying that Furuya Sensei was fond of, "Katte kara kabuto no o wo shime yo" which means After victory, tighten your helmet. Never let your guard down even if you think you have won. That just might be what your opponent wants you to think.