Seth enlisted in the United States Marine Corps in 2016, serving on active duty as a radio operator with 2d Tank Battalion, 2d Marine Division until 2020. He was honorably discharged at the rank of Sergeant (E-5). While pursuing his education at the University of Chicago, he continued his service with 2d Battalion, 24th Marines in the Marine Corps Reserve, and was promoted to Staff Sergeant (E-6) in December 2024. He currently serves as the Platoon Sergeant and Radio Chief for Headquarters & Service Company.