When a people missed the coming of their Messiah, it's not too hard to reply with such a statement. It's probably his way of suggesting that the Messiah will never come.
Suffice to say, I don't think Jesus was the Messiah. I could give a why or two, but I don't feel like starting a flamewar.
Suffice to say that Rabbi Johanan ben Zakkai's comment is part of a philosophy that God put us on Earth to do good on Earth. When God is ready to send the Messiah, He will send the Messiah. Until then, we continue to do what God put us here for.
Too many people have wasted too much of their lives, doing nothing but sitting on their elbows, waiting for the Messiah to come -- whether or not, it's the Messiah's first or second arrival. If you ask me, it's an unholy wastefulness of the life God gave people.