The following is a list of players who have at least 10 career retirement losses, and a career retirement loss rate of 10%+.
1. Yan Bai (China) 19.5%
2. Eduard Esteve Lobato (Spain) 15.6%
3. Bastian Malla (Chile) 13.7%
4. Wishaya Trongcharoenchaikul (Thailand) 13.1%
5. Adam El Mihdawy (USA) 13.0%
6. Michael Linzer (Austria) 12.9%
7. Adrian Obert (Germany) 12.5%
8. Aaron Cortes Alcaraz (Spain) 12.0%
9. David Souto (Venezuela) 11.8%
10. Reda El Amrani (Morocco) 11.5%
11. Omar Salman (Belgium) 11.2%
12. Martin Podzus (Latvia) 11.2%
13. Diego Hidalgo (Ecuador) 11.1%
14. Julien Cagnina (Belgium) 11.0%
15. Mats Moraing (Germany) 10.7%
16. Alexandr Nedovyesov (Kazakhstan) 10.6%
17. Nick Kyrgios (Australia) 10.3%
18. Denys Molchanov (Ukraine) 10.1%
19. David Vega Hernandez (Spain) 10.1%
To put that into perspective, Roger Federer has played 1459 career matches and has never had an in-match retirement. On the contrary, the often injured Juan Martin Del Potro only has a 7% career retirement loss rate. In fact of the top 1000 players in the world, only the above 19 players qualified for this list. Amongst the Top 100 players the average retirement loss rate is approximately 2-3%. Having a 10%+ rate is the elite retirement clowns in tennis. Of the 19 the only one ranked in the top 150 is Nick Kyrgios. Retirements are more prevelant in the lower ranks.
Why is this important? Because the majority of books will void your wager in the event of a retirement. Some books like Pinnacle, will grade Moneyline wagers if one set is completed, but they are in the minority.