Basic Expert: Suicide is not your only option

Retreat is a rare occurence in a Dungeons & Dragons game. A lot of the time it has to do with the Dungeon Master who is designing and/or running what is a one way death trap. 

In other cases it is the Players who fall into the habit of butchering Goblins until they are overrun, their resources exhausted (you saw Goblin Slayer ep. 1 - It was not pretty).

My Advice to Players: Always Retreat the instant you spot your first monster. It gives you the chance to discuss tactics. Assess the dungeon environment. Get away safely.