First, the Lord charges His servants to faithfully declare His messages, even if they are full of gloom and judgment. God tells Ezekiel that if His messenger (also sentinel, sentry, watchman, etc.) sees a sword coming upon the land and blows the trumpet and warns the people, he shall not be responsible for their failure to heed the warning; he will spare his own life. But, "if the sentinel sees the sword coming and does not blow the trumpet, so that the people are not warned, and the sword comes and takes any of them, they are taken away in their iniquity, but their blood I will require at the sentinel’s hand" (vs. 6). A prophet is liable for discharging the words of the Lord, no matter what.
Second, even when a preacher is heard and recognized for being such a watchman, the truth is his sacrifice is likely to be a futile exercise. For instance, how would you like Ezekiel 33:30-33 to describe your impact upon the world for Jesus Christ?
"As for you, mortal, your people who talk together about you by the walls, and at the doors of the houses, say to one another, each to a neighbor, “Come and hear what the word is that comes from the Lord.” They come to you as people come, and they sit before you as my people, and they hear your words, but they will not obey them. For flattery is on their lips, but their heart is set on their gain. To them you are like a singer of love songs, one who has a beautiful voice and plays well on an instrument; they hear what you say, but they will not do it. When this comes—and come it will!—then they shall know that a prophet has been among them."
To be regarded as a mere entertainer, someone who sings and puts on a show, yet is dismissed out of hand - how discouraging! God basically tells Ezekiel that the people will come to hear what he has to say, but will not heed his message. Yet, when his words finally come to pass and the people see the truth of it for themselves, they will recognize him as a prophet. But it will be too late!
Talk about a preacher's nightmare!