This reminds me of a chat room interaction I had maybe 25 years ago. The other person was adamant that humans can't see the infrared from TV remotes, and I was adamant that I could. It was pretty a widespread belief (even in school science books) at that time that humans couldn't see infrared. Since then more science was done to prove that, in fact, some humans can see some infrared under some conditions.

I share that mainly to state that humans are amazing and have a wide and inconsistent range of capabilities (and sometimes even mutating into new capabilities!) Personally, I will always hesitate to say "nobody" and I lean towards "no typical human" instead. :)

You can absolutely see corona discharge like that with your eyes.

If you come to my day job, and we shut off all the lights in the test room, after your eyes adjust in the dark for a minute, you'll see the soft purple glow coming from the edge our 160kV test rig.

Definitely emits UV, but there is enough visible to see it for sure. It comes from the electrons exciting nitrogen in the air.[1]

1. https://commons.wikimedia.org/wiki/File:Nitrogen_discharge_t...