First: This is pretty serious stuff. In fact, it's the stuff that history is made of. But, to the best of my knowledge, there is no other historical evidence for the "Egyptian" save for a brief reference by Luke (see The Reliance of Luke-Acts on the Writings of Flavius Josephus). In fact, there is much history that we tend to accept with little more that circumstantial/anecdotal evidence. So, my question to mythicists is this: is it reasonable to expect that the leader of a small Jerusalem cult would be better attested than someone apparently ready to move 30,000 men against that very city?