How does Polonius bring about his own destruction?

Meddling in Hamlet and Ophelia’s relationship places Polonius on the path that leads directly to Gertrude’s chamber and his fatal encounter with Hamlet. When Hamlet courts Ophelia, Polonius assumes the young prince has dishonorable intentions and forbids her to see Hamlet or accept his letters. He compounds his error by subsequently—and erroneously—assuming that Ophelia’s rejection of Hamlet has caused him to go mad. Having meddled in Hamlet and Ophelia’s relationship, Polonius acts to mitigate the damage he believes he has done and to circumvent further disaster by informing Claudius of what has transpired. “Come, go we to the King,” he tells Ophelia. “This must be known, which, being kept close, might move / More grief to hide than hate to utter love.” Ironically, with no understanding of the forces at work in the court or of his own errors in judgment, Polonius counsels Ophelia that it’s as natural for old men to jump to conclusions as it is for the young to lack discretion.
In meeting with Claudius shortly thereafter, the foolish and ever ambitious Polonius sees an opportunity to ingratiate himself with the king and seizes it. Convinced he knows the cause of Hamlet’s madness, Polonius offers to bring Hamlet and Ophelia together so that he and the king can eavesdrop on their conversation and confirm Polonius’s analysis of Hamlet’s condition. Has there ever been a time, he asks Claudius confidently, “[t]hat I have positively said ‘ ‘Tis so,’ / When it proved otherwise?” If there was, he challenges the king, he would like to know it. Polonius’s hiding with the king behind a tapestry to spy on Hamlet and Ophelia succeeds, but the next time Polonius employs the strategy, he dies, stabbed to death by an enraged Hamlet, who senses his presence and assumes he is Claudius.
When Polonius hides behind the tapestry in Gertrude’s chamber to spy on Hamlet, Polonius is unaware of Claudius’s crime, Hamlet’s real psychological state, and the dangerous political currents coursing through the court. He is also unaware of his inability to perceive the truth or to understand what is happening around him. In his ambition and arrogance, the foolish, meddling Polonius ultimately destroys himself.