Another reason why pro athletes may not like to retire is they love their sport too much, we need to remember that most of those that become pros start their journey as kids and they have been practicing for decades now, so suddenly finding out that they cannot do what they love anymore makes them feel lost.
However there are many ways in which an athlete could keep themselves close to their sport without playing anymore, like becoming a coach, an assistant coach, sports broadcaster and many other occupations that are closely related to the field.
I know why pro athletes don't want to retire, they'll lose fame, money and influence over people. However, Luis Suarez has osteoarthritis in his leg, that means that joint cartilage between bones are damaged. If he takes painkillers and continues playing, he will damage his joints even further and more rapidly. Then it will be just very hard for him to walk and do basic daily tasks. When he gets older, he might not be able to walk.
By the way, it's true that he can continue his career in sports by becoming a coach, broadcaster or something like that but if his transfer in Inter Miami gets officially confirmed, then he will have to play on the field. If he plays on the field, his health condition will get worse and that's what I am afraid of. He has to stop for his own betterment.