I don't think Russell was necessarily crazy. He was a man of his time, and his beliefs and actions were not terribly out of the norm for his time and place in history. He was successful on many levels, as a businessman, author, and charismatic preacher.
Frederick Franz on the other hand was a bit of an oddball character. Whereas Russell was successful because he could appeal sufficiently to society in general to generate a following, Franz could only thrive among the captive audience of pre-existing believers. The general public flocked to hear Russell in many places. Thousands of the flock were wowed by Franz too, but not including many who were not already JWs.