What's the lifetime of a Dyson megaswarm?

Among the forces that would work to destroy large megaswarms are radiation pressure from the star, the star's oblateness and gravitational perturbations from other bodies in the solar system. For example, Jupiter would cause the destruction of a megaswarm at Earth's orbit in just a few hundred thousand years, Lacki calculates.

He speculates that an advanced civilization, especially if using their swarm for solar power like a Kardashev II civilization would, might well strip all planets and asteroids from its solar system to minimize the chances of the swarm's destruction from gravitational perturbations.

A Kardeshev III civilization, aiming to capture all its galaxy's starlight, might strip all planets from the galaxy, leaving it otherwise barren and devoid of life. Once the galactic megaswarm is destroyed there will be no possibility of life restarting anywhere in that immense region of space.