Try not to feel too bad, Froggie. He could indeed be taking advantage (well — he IS, really), but it may be more desperation than nefarious. Backpacking & ran out of money or got taken advantage of by someone else, or just bad luck — and you were kind enough to bail him out. As long as you’ve got eyes on him and he’s doing a good job otherwise, maybe think of yourself as a good samaritan vs a “mug,” and it won’t sting so much.
My daughter said something recently that’s stuck with me: if she gives money to 5 people, maybe one is a scammer, & that sucks. But she chooses to focus on the other 4 people who likely really needed it, and the help she gave them is worth way more to all of them than the $20 the potential scammer got off her.