Imagine if you were not only present, but you had a vested interest in believing this guy was the messiah. If he was one of your people and fulfilled the prophecy you've been staking your entire worldview on. Imagine you were a Jew in the presence of Jesus.
Yet, many Jews did not buy what Jesus was selling. Many did, sure, but considering the Moses-level miracles...why not all? Or at least 99%? If there is something I'm not getting about history, please let me know, but the way I see it, how am I supposed to accept claims two thousand years removed with here-say records when so many of the contemporary neighbors weren't impressed.
Maybe, just maybe, the "miracles" just weren't impressive.