@FireFox
That still doesn't make sense though, and it's because of what you pointed out. I don't care how powerful a goblins is, Kingdoms do not fall in a week span, especially if the Demon King was almost killed meaning they're militaristic right now. You don't need to kill the goblin, at worst, you just suffer the siege for 7-days and poof, problem gone.
Even if we forget that, If a single goblin is dangerous, it must have enough skills that a dagger is still not going to be the appropriate tool to kill him. Maybe an arrow would work better from a distance, but a dagger is not the correct item. Unless this just happens to be a skill sealing device in the shape of a dagger.
@juntaksadis
Not necessarily, or to state another way, to MC the bet was of equal value. Granted, the count was planning on cheating from the start, so he didn't care what he bet, the point wasn't what he would or wouldn't win, but to test MC. Meanwhile, MC viewed the bet of being a good proposition.