Refillable vs disposable pens
Once a pen has finished its serviceable life, or lost - which is most often the case, it doesn't simply disappear into thin air, although it may seem that way the rate they seem to vanish when you need one.
These disposable pens ultimately wind up in landfills and in waterways. Being made of plastic, they don't break down quickly and plastics are also usually made from crude oil.
A good refillable pen can last a lifetime. However, they do use cartridges which need to be disposed of. The cartridges are metallic, so they can be recycled.