Here's why and some factors to consider:
* Hair Follicles: Hair grows from follicles beneath the skin. Cutting the hair doesn't damage the follicle itself, so the follicle continues to produce hair.
* Growth Cycle: Facial hair, like all hair, goes through a growth cycle (anagen, catagen, telogen). Cutting the hair only affects the visible hair shaft, not the underlying cycle.
* Rate of Growth: Facial hair generally grows faster than scalp hair.
Important Considerations:
* Damage to Follicles: If the follicles are damaged (e.g., by severe burns, radiation, or certain skin conditions), hair may not regrow.
* Plucking/Waxing vs. Cutting: Repeatedly plucking or waxing hair *can* sometimes damage the follicle over time, potentially reducing hair growth, but this is less likely with facial hair than with, say, eyebrows. Cutting the hair shaft has no such effect.
* Medical Conditions/Medications: Certain medical conditions or medications can affect hair growth.
* Age: As people age, hair growth may slow down, and hair may become thinner.
In summary, unless there's damage to the hair follicle, cut facial hair will almost certainly regrow.