Sylphs are a race of monsters with small bodies and extremely cowardly guts. They are even willing to sell other members of their race for their own safety.
This was because sylphs were so weak, they didn't even have the strength to protect themselves. However, their beautiful and cute shape makes humans reluctant to kill them.
Most of the humans just catch them and keep them as pets like birds at home.
So it can be said the sylph's cowardice is a form of self-defense against danger. And strangely, the sylph's cowardice is effective for all types of predators and even brainless animals will release them after seeing the beauty, cuteness, and cowardice of sylph.
However, apart from their appearance and nature, the sylphs also have other abilities to protect themselves. With their small and almost transparent bodies, it would be very difficult to locate sylph in the middle of a wilderness like the Bog forest.