Headcanons!!! And something else
I have a feeling that Pyro isn’t just out of his mind, but might also be deeply traumatized? These kinds of "abnormalities" usually stem from genetics, physical trauma (like a head injury), or psychological trauma. If we consider that Pyroland mostly replaces CRUELTY (plus the fire), maybe he really is deeply traumatized? Judging by what we saw in "Meet the Pyro" and the comics, his pyromania might be more intuitive, triggered because it also manifests Pyroland. Alternatively, it could have developed long before the "trauma" and remained on a subconscious level...
Like, if you look at HOW Pyroland replaces the cruelty around Pyro, it feels like there could have been such a severe event in his life that his brain completely cut itself off from reality. Plus, this could easily be combined with a brain injury ? Mental struggles like this often arise from trauma, since psychosis and dissociative symptoms frequently go hand in hand with trauma spectrum disorders and similar conditions. . . . Also, since we know NOTHING about his past, it leaves plenty of room for speculation. Moreover, his pyromania is likely more intuitive, something along the lines of "when I do this, it brings me joy and the world becomes brighter", while to the other mercenaries, it looks like he can’t survive a single second without burning things. Plus, Pyroland itself seems to have a cumulative effect, because in the comic, Pyro could see Pyroland even without fire or any extreme violence around (until he beat the bear, of course), so... yeah. Plus, we don’t know how Pyro perceives himself.
As someone diagnosed with PTSD (2 years ago) who now strongly suspects having C-PTSD due to certain reasons, along with MADD, dissociation issues, and other struggles, I constantly see bits of myself in the Pyro's behavior in the comics. So maybe this is just a projection and a self-insert, but theoretically, it could provide at least a minimal justification for this theory!!!
P.S. I use he/him pronouns for Pyro here because it's a habit 'cuz I mainly in the ru/ua TF2 community, but I completely positively view any other pronouns ^_^ I'm not a nonby-phobic or smthng worse . . . Sorry, I'm very nervous before publishing !
P.P.S.: I know that Pyro has very sturdy gloves made of high-quality materials, I just like to think about it this way. Why not? I don't think it would happen after literally every single round, just once in a blue moon. + I'm just used to drawing Pyro with bandaged hands by now !