It seemed like a significant expense, but in reality, the costs weren't as high as imagined.
It was just Alliance currency, and much of it was just promissory notes.
What's the use of issuing Alliance currency? If adventurers spend it immediately, they're spending the savings that Gu Hang pulled together from various places in Rubbish Town. If they hoard it without spending, it represents future redemption.
Truthfully, if one wanted to be nasty, it would be easy to talk about integration into the Alliance system and converting to work points in the future; for those who want to leave and cash out their Alliance currency, you don't get to set the price of goods anymore.
Of course, Gu Hang wouldn't do this unless absolutely necessary, as it would be quite damaging to his reputation.
Gu Hang still hoped that these people would be able to stay in the future.
Even if they didn't remain soldiers, transforming into workers would still mean a population of a hundred thousand.