Sin is blinding.
It seems so obvious to us as we're reading this passage. Every one of Jeremiah's prophecies have come true. According to every measurable evidence he is clearly a prophet that speaks the Wird of God as directed by Him. And now this prophet is once again prophesying, very clearly, what will happen if they go to Egypt.
And the people don't listen. Not only do they not listen, they accuse him of being a liar and false prophet, and leave for Egypt (and certain destruction), forcing Jeremiah to come with them.
Sin is blinding. Willful disobedience is heart hardening.
It seems unimaginable to us. Stupid even.
Are we guilty of the same thing? Are we determined to do what seems right to us, instead of listening to the Word? Are we asking God to give us a sign or give us peace about a decision, when He's already given us the answer in His Word, but it's not the one we wanted so we keeping asking the same question different ways hoping someone will give us the answer we want and justify our actions? If you try hard enough you can always find someone willing to tell you what you want to hear. But, just like for the Israelites, that path inevitably leads to destruction.
May we have faith to take God at His Word and obey, even when it's difficult or the last thing we want to do. He is Truth. And He is good. Trust in Him alone.