It's not that people suddenly stop caring at 50, it's that if you lose your hair in your 20s and 30s and still care at 50, then the hair wasn't the problem. I don't care what it is, 20-30 years is enough time to find healthy ways to get over something.
If people have hair their entire lives but start going bald at 50, some of them are going care as if they were 20. They just lived 50 years with hair. That being said, many guys deal with being bald a lot better then others. I know several bald guys in their 20s that handled it just fine and have normal social lives, girls/fiancés/wives. Not everyone carries the same mental burden from losing their hair, whether 20 or 50.