preventing my printer nozzle from getting too dull, from nothing but PLA filament I had a new Extruder tip on my Ender 3 3D printer. the tip looked like the left tip in the below image. After I have been using it for about 5 months, the tip got dull/flat, like the tip on the right in the below image.
The only filament I have used is a spool of  PLA (from hatchbox) and a spool of PETG (from sain-smart)
About the Filament
From the time that I replaced the tip, to now, i have only used my 1 spool of PLA filament.
I don't believe it has any carbon-fiber in it, the only other things I can think of, are that the filament has a tough time sticking to the bed, so I have to print pretty close to the bed.
Image of my 3D prints using my PLA filament

Image of my PLA filament


I don't 3D print a terribly large amount, Is it normal to have to be replacing the pen this often?
How do I prevent my extruder tip from getting dull so soon? Is there a way to prevent the pen tip from getting dull at all?
Actual Images: (Sorry for all the edits, I’m trying to add the images on my phone and it’s not working)
Your extruder nozzle will wear from the inside out if you are using abrasive filaments, which include carbon fiber, wood type filaments, glow-in-the-dark and many other types.
Because they are abrasive, removing material from the inside also thins the cone shape of the outside (point) of the nozzle.
The solution is to not use abrasive filaments, or to use a hardened nozzle specifically manufactured for abrasive filaments, or to change the nozzle frequently.
If this is a 3D printing pen as your post suggests, please clarify, as the answer is likely to change but only slightly. If this is a nozzle for a 3D printer, consider to edit your question to reflect thusly.