Wittgenstein seemed to have had a morbid fear of not being understood. James Klagge says some interesting things about this in his book Wittgenstein in Exile. But, perhaps he makes too much of it. And, perhaps, at times, Wittgenstein did too.
Shouldn't he at least have shown us a glimpse of the irony in the very idea of there being a private Wittgenstein, someone who uses words and has thoughts only he can understand? Recall, it wasn't just Joanna or Joe Soap who would be left in the dark - even verbally astute philosophers like Russell would not be able to understand him. At the same time, isn't there something dubiously realist, and unWittgensteinian, about the notion of there being words and thoughts the meaning/content of which are unavailable to others?