After a superb time with Chelsea, Hazard struggled with his fitness at Real Madrid and eventually retired at the age of 32.
"I think he quit too soon, but I understand him. He had a good reason," Desailly told The Independent.
"People think football is easy, but for a player it's about being able to live with the pressure, the training and the lifestyle. When you can't do it anymore, then it's right to stop."
Desailly, who himself played for Chelsea between 1998 and 2004, believes that Hazard did not feel the same security at Real Madrid as in London.
He added, "At Chelsea he was protected and could shine with his talent. At Madrid he needed to give something extra – in training, in his diet, in his everyday life. Maybe he couldn't take it anymore."