Some do, some don’t.
In the places where my husband and I grew up, a Catholic man wearing a crucifix either meant he was a deacon/ Church minister type (usually older men) or just a reflection of ethnic background, with Italian and Hispanic men being more likely to wear a crucifix or a visible medal than men of other ethnic backgrounds. My husband always thought of it as being an Italian thing because all the Italian guys he knew in high school wore stuff like that.
If a young man doesn’t want to “wear jewelry” then I can understand that and I would suggest that he instead have something pinned to his clothing (could be in a place where it does not show, even) or something he can carry in his wallet.
Edited to add, and yes if the boy plays sports or works around machinery of any kind, it can be a health hazard to have anything loose dangling.