Bey was born Apr. 9, 1999 in Charlotte, North Carolina but grew up in Largo, Maryland. He is the son of Drewana Bey, a high school principal who played college basketball at Charlotte. As a freshman, Bey attended DeMatha Catholic High School before transferring to Sidwell Friends School, known for its strength in academics and basketball. Bey also played AAU ball with D.C. Premier. He helped lead Sidwell Friends to a state championship as a junior, averaging 14.5 points, 6.5 rebounds, 2.0 assists and 2.0 steals per game. As a senior, he averaged 21 points and eight rebounds per high school contest. For college, Bey originally committed to NC State, then de-committed and opted to attend Villanova one month later. As a sophomore at Villanova, Bey won the Julius Erving Small Forward of the Year award and was named to the First-team All-Big East. Bey progressed from a "glue guy" to a primary contributor between his freshman and sophomore seasons at Villanova. He took a bit of a backseat in the scoring department to the likes of Eric Paschall and Phil Booth his freshman year, but still managed respectable averages of 8.2 points, 5.1 rebounds and 1.3 assists. That was enough for a nod on the Big East All-Freshman team in 2018-19. With the aforementioned players gone for Bey's sophomore season, he was forced to take a much bigger scoring role. Bey put up 16.1 points that year, which included a career-high 33 points Jan. 11 against Georgetown. He racked up plenty of accolades for a Villanova team in the running for a No. 1 seed, including an All-Big East first-team nod and being named a Wooden Award finalist. He also won the Julius Erving Award, given to the top collegiate small forward.