You never bit on your pen? Especially back in the school days?
Ballpoint pens are the OG stress relief / concentration / "fidget spinner" toys. Except the BIC ones, those would easily shatter; suddenly finding your mouth to be full of sharp, orange or translucent shards of plastic, is the opposite of calm and focus.
I've never done that because pens end up in the dirtiest places. People aren't washing their hands before using them, they gets tossed in a bag and sit in the crevices alongside all sorts of dust and dirt, they get set on dirty desks and will even hit the floor sometimes. All-in-all, super gross.
Thereby proving that Coke Bottle and BIC pens are meeting a need. They are not perfect (what is) but they are good enough to sell billions upon billions of product. Pretty hard to argue against overwhelming success.
The flimsy cap gets lost easy and there is an endless amount of ballpoint pens you can click, that don't even need a cap in the first place.
Average clicking ballpoint pens have a plastic that's more comfortable to suck, lick and bite.
I always hated them.