As Joe Rogan pointed out recently, it's understandable that it might be incredibly hard for fighters to walk away from MMA. Especially when all you've got to show for your time in the cage are two bad shoulders and a tough case of cauliflower ear.
Nevertheless, some fighters simply hold on too long. Hey, it happens everywhere; it's not like it's exclusive to MMA. But with MMA, there is an added edge, because a stubbornness to leave the fighting arena can mean you're endangering yourself.
Here's the top 25 list of those guys I think have stayed on too long.