If you're a man that didn't sign up between 18 and 25, you permanently lose student aid in most states along with federal employment eligibility. Some even ban getting a driver's license. In practice, it's young men of lower socioeconomic statuses that are failing to register. This is due to lack of knowledge or presence in the system more than conscientious objection. e.g. Prison or being homeless. Many choose to ge…
According to the Federal Office of Personnel Management, only 1% of cases of nonregistrants adjudicated by OPM result in denial of Federal employment. Almost everyone who appealed a denial got their job restored:
https://www.govinfo.gov/content/pkg/FR-2024-02-07/pdf/2024-0...