Why are monopolies problematic? What are 2-3 issues with monopolies?

Monopoly simply means a business that is a sole provider of a particular service. Mentioned following are some issues with monopoly:

a) As sole providers, they can raise the prices whenever they want.

2) They can supply low-quality products as consumers have no option, expect them.

3) They restrict free trade in the market. and sometimes own small venture to retain their sole character.