Ushijima has never hesitated to take as much advantage of others as possible. The only reason we haven't seen this more aggressive method before is because we've mostly seen gambling addicts, who aren't looking to spend their money on any other things. That's the core of his business so we saw it first. This time, there was a more lucrative alternative to a few illegal loans, so he took it. He's utterly immoral, he's a vehicle to show the reader the ways that foolish people are taken advantage of. I prefer this manga over "Shinjuku Swan" because this author doesn't have a MC who's unrealistically committed to acting ethically.
Also, I bet that instead of a good ending, it'll end with her original plan working out as intended, but by then she'll have lost even more on these frauds, so everything will still be fucked for them. Maximum suffering.