Monopolies in and of themselves aren't a problem, and aren't illegal. Unfair leverage to prevent competition is.

This is not correct and a common misconception, on both sides of the argument.

Both monopolies and monopolistic actions are illegal, each alone is enough to be in violation of the law.

The existence of competition doesn't always make things better. For example forcing middlemen to exist so that there is competition can lead to a worse situation than without middlemen. Direct to consumer is unfair leverage to middlemen, but it can be better for consumers.