Is it worth entering into an unequal battle with evil, if your fight is practically doomed to defeat?

This is a reasonable question when you have a choice: to join or not? And when you are stuck in a dead end, there is only one reasonable (I mean, rational) solution - a duel! Small chances are better than no chances at all. To try is a very important mission. For example, in "The Plague" by Albert Camus, the main character Dr. Bernard does not imagine it that way: "I am just doing my job", but he is a desperate hero who challenges a powerful (otherworldly) force. The same role is played by the protagonist of the play "The Dragon" by Eugene Schwartz. He challenged the dragon despite the obvious superiority of the enemy. I gave this example for four reasons:
1) the archetypal nature of the dragon-fighter
2) he succeeded at the first attempt - it was worth starting
3) in case of loss, he would have lost his life, but he still dared
4) even the people he was rescuing SAID HIM NOT TO FIGHT.
His victory is a positive black swan (see Nassim Taleb), which has a very high value. The value of winning outweighs all negative outcomes. This choice loses to the refusal of the fight only by the unpredictability of the results.
Thus, a challenge is worth accepting when the expected benefit from winning exceeds the sum of expected losses from losing. This is a rationalistic solution to a philosophical (and sometimes everyday) problem.