Daniel 5:22 (ESV)

22 And you his son, Belshazzar, have not humbled your heart, though you knew all this,

Belshazzar knew these things. He should have learned a wise lesson for himself from this history. It should have brought him to awe of the only living God. It did not. He followed in the footsteps of Nebuchadnezzar by exalting himself, even now when he is so distressed.

Belshazzar, during the time of his reign, did not recognize the Lord as the Almighty who appoints kings when and where he wills. He has lived as if he, in his own might, has the power and can do with it whatever he wants—as if there was no one greater than him.