No, this isn't character develop, what did Joshu learn? Did he mentally grown? No and no, this is just a unnecessary arc, it's like Araki wanted to give Joshu some protagonism and develop, but that don't worked at all.
I’m starting to like joshu, and I don’t mind filler stuff but this was not character development...he said he was gonna beat the shit out of the guy and the whole time he was greedy with the money. Not every character can be morally good, joshu is just an ass and sometimes having asshole characters is necessary 🤷🏻♀️
He can't buy anything, thats true. But my guy can just walk in to a shop, grab a switch, break it with his bolts nuts thing and "pay for the damage", they would either say its their problem and return his money and he will keep the "broken switch" which he can just bolt back again with his stand or they will accept the payment and free him from the curse.