Monopolies affect the scope of choices you make, especially as they expand their interests. You can, say, choose not to register on Facebook, but at a certain point, that choice is synonymous with not keeping in touch with your friends. You can choose not to pay for the crappy service from one particular internet provider, assuming there is another competitor with better service. You can choose not to subscribe to this or that online video service, but that is also choosing to miss out on their exclusive content. You can choose, as an artist, not to list your music on iTunes or your books on Amazon, but you'll be cutting yourself off from 90% of sales. The more power an individual company has, the less free you are to choose not to do business with them, because that choice means more than boycotting one individual company. Often it means boycotting an entire line of business instead.
Mokalus of Borg
PS - When you can't afford not to do business with someone, that's a problem.
PPS - Whether it's a monopoly or not.