I have often thought that the prophet I would least like to be is Yirmiahu. What a miserable job to have, to warn and to warn and to warn, all the while knowing that you are being ignored! And then to watch all your most dire predictions come to pass.
I think this might be why he tells us in the opening lines of his book that he was given his task as a very young child; such a task would be too difficult for someone who grew up in a conventional way, with a conventional sense of hope and optimism.
Yet, we should not worry that his lifetime was all for naught.
First of all, the fact that his book is still in print with the rest of the prophetic writings we have means that his messages are still relevant. His prophecies don’t alter his future, which is now our past. But he tells us what led to past failure of his Jewish world. And they are the same things that lead to our communities’ failures. A main feature he condemned was the over-emphasis on ritual elements of our lives that clouded our judgment of human frailties like selfishness and cruelty. I alluded to this in my post about Jerusalem.