Why is the Kármán line altitude significant in terms of flight capability?

Answer

An aircraft would need to achieve orbital velocity to remain airborne.

At 100 kilometers, the air density is so low that conventional aerodynamic flight is no longer viable; an aircraft would require orbital velocity just to generate enough lift to stay up.

Why is the Kármán line altitude significant in terms of flight capability?
SpaceorbitISSaltitudeKármán line