Demps was born in Portland, Oregon to Serene Hill and Dell Demps. He moved frequently as a child due to the elder Demps' career as a professional basketball player and as a basketball executive following his retirement until ultimately settling in San Antonio, Texas after Dell was named the director of player development by the San Antonio Spurs. He attended and played basketball at Ronald Reagan High School and was named All-District twice. After averaging 19 points and four assists per game as a junior, Demps committed Northwestern over offers from Minnesota and Colorado.
College career
Demps played five seasons for the Wildcats, redshirting his freshman year after suffering a season-ending shoulder injury after four games. He finished his collegiate career with 1,518 points, 353 rebounds and 288 assists over 132 games and was named honorable mention All-Big Ten during his redshirt junior and senior seasons when he averaged 12.5 and 15.7 points per game. Following his redshirt senior season, Demps participated in the Portsmouth Invitational Tournament and led his team in scoring in each of its three games and averaged 16.3 points per game overall.
Professional career
Belfius
After going unselected in the 2016 NBA Draft, Demps was signed by Chicago Bulls to their NBA Summer League roster but did not receive any playing time. Demps then signed with Belfius Mons-Hainaut of the Belgian Pro Basketball League on July 20, 2016. In his first season of professional basketball, he averaged 14.2 points, 2.1 rebounds and 1.8 assists in 38 games. In his second season with the team, Demps averaged 13.6 points in 37 PBL games and 16.1 points in 16 games during the 2017–18 FIBA Europe Cup and was named to the Eurobasket.com All-Europe Cup 2nd Team and to the All-Imports Team.
Demps signed with Vanoli Cremona of Italy's Lega Basket Serie A on July 16, 2018. Cremona announced that Demps and the team had agreed to part ways on February 25, 2019. Demps averaged 10.5 points, 2.1 rebounds, and 1.2 assists in 17 games for Cremona.
Demps signed with Kolossos Rodou of the Greek Basket League on February 26, 2019. He played in 10 games, all off the bench, and averaged 8.4 points, 3.0 rebounds and 1.6 assists per game as Kolossos finished last in the league with a 5-21 record.
Demps returned to Italy after signing with Cestistica San Severo of the Italian second division, Serie A2 Basket, on July 29, 2019. He averaged 18.6 points, 3.6 rebounds and 3.2 assists per game.