It’s obvious some players go out of their way to wear necklaces on the outside of their uniforms. Certainly there’s no need to let other players and fans know they got a few bucks. So, why do they do it?
Why does anyone wear a necklace?
I assume the answer would be the same for baseball players.
Lots of reasons, some related to superstition.
Are there a lot of situations where ANY piece of jewelry is “needed” to let people know they got a few bucks? Answer that, and you have your answer.
If you’re still stumped, it’s because they like how they look with jewelry on, or that jewelry is particularly meaningful to them. The exact same reason 99.9% of all jewelry is worn.
“How do they go to the bathroom with all that on?”
If you know, you know.