I have watched Ant-man and the Wasp. In the post credit scene, Ant-Man's friends all disintegrate except for him, being trapped in the Quantum realm. What was the reason for why he did not also disintegrate? Is he too small to turn into dust, or is he one of that half of 'lucky' people that didn't turn into dust? Or is it because of something else?
Probably Ant-Man was a lucky one.
In this break-down of the post-credits scene it's said that there is correlation between Infinity-War affects and Ant-Man.
It would appear that the rooftop scene takes place concurrently with the end of Avengers: Infinity War when Thanos snaps his fingers, randomly halving the universe.
- Ant-Man and the Wasp Post Credits Scene - CNET