Balak and Bilaam go out a few times to try to curse the Jews. Each time Bilaam tries to curse, it comes out as a blessing. Each time, Balak gets increasingly more upset at Bilaam, screaming at him more and more.
Why did Balak keep trying. Bilaam told him he can only say what Hashem allows himm and after seeing that Hashem would only allow Bilaam to bless, not curse, Balak should have said let's go home and have a beer instead. Why did he keep trying?
The events show that a person can get caught up in what he sees as reality because of his personal interests. He can completely ignore everything else, because he is completely focused on one thing.
Balak was so determined to curse the Jews that he completely blocked out any objective evealuation of the situation. He did not even see that he had no chance of success and that he was accomplishing the exact opposite of his goal. He fooled himself into thinking he could still do it.