I honestly believe it’s confidence. There’s nothing wrong or particularly ugly to me with thinning/balding hair and I know plenty of really handsome guys who are losing it up, but I feel a lot of them get really self conscious and it’s a blow to their self esteem. They try to hide it with hats or combing their hair a certain way and you can just tell they aren’t their most confident self. Shaving it just says to me “my hair or lack of it doesn’t define who I am” and I find that attractive.
The guys I know who’ve shaved their heads whether for balding issues or purely aesthetic ones - I think they rock it with a new found sense of self and pride and the confidence is sexy.
That’s my take as a prematurely grey 27 year old lady anyway. Not trying to compare the two, but it was a hit to the self esteem when it began happening and I’ve since learned to embrace it and my salt n pepper hair is now one of the more interesting features I have.