I wouldn’t go so far as to call him stupid for having no hesitation to save someone, including a total stranger, even if it meant using a powerful card. What I’d call him stupid for, is that he often forgets to check his phone and the news for anything important. This is the main reason he’s mostly never up to date with what’s happening around him, and why he ends up usually late or whatnot.
Not sure who I was replying to for this second bit, but main reason he never joined the raid is because his mother just woke up and he’s afraid she’d be traumatized if she found out he’s a hunter considering what happened to his dad, plus he also had faith that the other S hunters would do the job right. The MC also really lacks awareness of his own strength.