e.g. "Progress comes from monopoly, not competition" — Peter Thiel
That said, lack of non-compete enforcement is often credited as one of the contributing factors to California's excellent startup environment.
Certainly seems to be Amazon's pitch that it is in fact fairy dust when they're driving their competition out of business.
Intellectual property is also a government-protected monopoly, created for the advancement of society.
Basically I'm saying that monopoly can be good or bad depending on the specifics. So competition can be very destructive in some cases.