An enthusiast of tennis, Ein founded the World TeamTennis (WTT) team Washington Kastles in 2008, and has chaired the DC Open since 2019.

[1][8] Ein bought the Washington City Paper in 2017 and became chairman and CEO of the DC Open tennis tournament in 2019.

[9][10] He is the chairman of the board for Kastle Systems, a security company, and CEO of Capitol Investment Corp.[7] Ein founded the Washington Justice of the esports Overwatch League in 2018.

[6][14] The same year, he was a part of an investment group led by Josh Harris that bought the Washington Commanders of the National Football League (NFL) for $6.05 billion,[15][16][17] the highest price ever paid for a sports team.

by the Village People and was attended by over 350 guests, including Mark Warner, Ted Leonsis, Raul Fernandez, Vernon Jordan, Valerie Jarrett, Debra Lee, Gene Sperling, Larry Summers, David Bradley, Adrian Fenty, Jack Evans, Murphy Jensen, Sam Kass, Capricia Marshall, and Mitchell Rales.