Jeremiah was not a happy man. There were many happy people in Israel at the time, many upbeat, optimistic and pleasant folks, including a number of other "prophets". As a rule, these people did not like Jeremiah, because they did not like his unpleasant message.
The pleasant prophets spoke encouraging words to the people. They affirmed the people. They assured the people that the Lord was with them, and that they would soon see the mighty hand of God working things out for the best. I guess you could say that these pleasant religious leaders were kindly and pastoral.
Jeremiah, on the other hand, told the people and the leaders that they would soon become slaves to the pagan king Nebuchadnezzar. Moreover, he told them that this was God's will, that the decision had been made, and there was no longer any other way. There had been a day when repentance and prayer would have turned things around, but that time was in the past. They might as well get used to the idea of serving the pagan king, because that was to be their lot for the next 70 years.
The pleasant prophets said, "Not so!", that there was always hope, that if the people would just put their trust in the Lord, the Lord would surely deliver them. With few exceptions, the people heeded the pleasant prophets, because they were attracted to the optimistic, affirming message of hope.
It would seem that we live in Jeremiah times.