I read that Kashiram was a wealthy devotee. Why did he become angry and refuse to give Maharaj Dakshina when his finances declined?

This appears to be a misunderstanding of the events described in the source material. The account in Chapter 0 states that Kashiram would feel very bad and get tears in his eyes if Maharaj *didn't* take Dakshina from him. When Maharaj later caused Kashiram's finances to decline as a leela to remove his pride, Kashiram did not refuse to give. On the contrary, he remained obedient, following Maharaj's instruction to "Borrow from the grocer and bring it to me," even when he had to go into debt to do so.