They were considered an agricultural pest.
“Outside of the breeding season the parakeet formed large, noisy flocks that fed on cultivated fruit, tore apart apples to get at the seeds, and ate corn and other grain crops.”
https://www.allaboutbirds.org/news/carolina-parakeet-removal-of-a-menace/
" The bird’s diverse diet, which included cultivated seeds, fruits, flowers, nuts and corns, also angered farmers who killed them to protect their crops.
These social birds had a close bond with each other and when one died, the rest of the flock would shriek and gather around it. This made them an easy target and [hundreds were killed in one go]"
https://www.nhm.ac.uk/discover/news/2021/july/reviving-the-cold-case-of-the-carolina-parakeet-extinction.html
“Farmers, who saw them as crop pests, easily eliminated whole flocks, since the animals had the unfortunate habit of gathering around their fallen comrades.”
https://www.nationalgeographic.com/animals/article/carolina-parakeets-extinction-birds-united-states
“…they were killed in large numbers because farmers considered them a pest…
A factor that contributed to their extinction was the unfortunate flocking behavior that led them to return immediately to a location where some of the birds had just been killed. This led to even more being shot by hunters as they gathered about the wounded and dead members of the flock.”
https://johnjames.audubon.org/last-carolina-parakeet