Thanks for the chapter.
Seems a bit unrealistic that absolutely nobody would be willing to dive into dungeons. Like even if this is a world where dungeon/isekai media or culture doesn't exist, there must be at least some religious types or cultists who see an opportunity.
The Japanese dungeon program is run by the Ministry of Defense (and is pretty much the only program that's progressing). So they're still sort of limiting access. You aren't getting World Class Athletes showing up at recruitment drives (who can easily get a better paycheck safely outside), you're getting normies, who are getting hurt and making the whole program look bad. The whole point of this recruitment drive is to get more legitimate people to show up.
In terms of Isekai, no one aside from MC actually has shown any Isekai type powers (And he's keeping them secret). So, if you tell a random guy, hey, fight monsters, you don't really have a lot of people who think they have the strength or the skills to actually do so. If they entered a dungeon and /all/ got powers, then you're getting isekai media fans flocking.
Aside from the wish fulfillment of this new recruit, the lost generation is a serious issue for Japan, you'll get a fat guy that turns into a hunk. Which increases the subset of the population that can/want to go into the dungeon.