Jeremiah 21

Jeremiah had the task quite frequently of telling people things that weren't so good. Things they probably didn't want to hear.
In this case a contingent comes to him with hope, wanting to ask God if He could do for them what He had done in the past. Could He rescue them from Babylon?
God's answer in this case is not positive- if you want to live: get out of the city!
I would have left the city right then! If God's answer is no to what you want, He still offers a path of life out of the difficult situation.
In the case in this chapter, the people of that city had created a problem and apparently the only way to fix the problem was to destroy the city. Sometimes fixing a problem requires destruction. But there is always a path out.