So, the 4 monsters are "board of directors" for the dungeon? And the dungeon is somehow run as a business. I wonder what its business model is like? It doesn't seem to be based on just the time the adventurers spend in the dungeon, otherwise male lead being there would have solved all their financial problems long ago.
Or maybe that's how they built themselves a 100-floor dungeon in the first place?
On a positive side, succubus getting fired from so many dungeons suggests that dungeon monsters respawn when killed. Otherwise, she would not have survived so many failures.