We all know about how Simone Biles signed with UCLA, but changed her mind and went pro. Here are some others who could have been Bruins or were just briefly Bruins but left and achieved the most success elsewhere:
Rai Benjamin (Track - two gold metals) - Competed for UCLA as a freshman and soph and then transferred to USC where he won two NCAA titles.
Sondre Guttormsen (Track - 8th place Pole Vault) - Competed for UCLA as a freshman. Then transferred to Princeton where he won three NCAA championships.
Mallory (Pugh) Swanson (Soccer - gold metal) - Enrolled at UCLA as a freshman but turned pro before the season started. Tied for the tournament lead in total points with 10. Scored game winning goal in gold metal game.
Trinity Rodman (Soccer - gold metal) - Originally committed to UCLA but changed her mind and went to WSU with her brother. Second most goals (Swanson first) on team.
UCLA took credit for all but but Biles and Rodman.