It seems wondrous and strange that Tzaddikim need to take charity for their livelihood. Shouldn't they receive their sustenance directly from the hand of our Father in Heaven?
Rebbe Elimelech of Lizhensk answered that this happens so that certain people can draw close to the Tzaddikim to rectify their Nefesh- Ruach- Neshamah (Life-Spirit- Soul-three components of the soul)by associating with the Tzadikim through the money they give him. Sometimes someone will come to a Tzaddik and request some physical benefit from him, but the Tzaddik can see that his soul also needs rectifying Since they are not aware of it, H'shem sends them some other reason to seek the Tzaddik, and they must go to the Tzaddik to ask him to pray on their behalf. With the money they give for the Tzaddik's help, he can do good for their soul as well. MiPeninei Noam Elimelech 222