Man, I just see people hating on the mc I'll just have to chip in.
+MC is orphan, everyone calls him useless (important)
+Hot elf takes him in, becomes strong
+Wants to become even stronger, makes pact with devil (hollow)
+Devil said the more you pay, the better the pact
+Got a mysterious devil that demands his remaining potential (just a level below than taking his soul)
+This gotta be good shit
+Comes this little guy, baphomet guy said he's useless
+Flashback everyone said he's useless before, gotta back this little guy, takes the pact anyway
+Adventurers said his skill is useless because not enough boom boom, but not realise it's wayyy useful outside battle. Imagine using Holy Bottle but it lasts the whole game. Like casting Estoma and it never wears off, you can fucking sleep in dungeons.
People literally wants to sell pocket aircond with his power.
I'd say his mistake is trying to be an adventurer. If he becomes a merchant and sells eternal lamps, heating and fridge he's already bathing money.
Y'all calling him idiot has the same level of IQ of the in-universe idiots. Everyone wants big dakka but nobody realises how useful electric-free all year around, almost no maintenance electric fence, covering the whole county to boot. Also there's this whole manga genre of "useless guy but OP when he changes field", haven't you guys learned by now?