Actually a lot of people are forced to buy Apple devices. See Apple's educational efforts as a good example of that.

Am I missing something?

Yes, you are -- Apple is big enough, and dominant enough, that even without a monopoly they can exert significant control over the rest of the market. How often do we hear on here -- strangely by people gloating on Apple's behalf -- that they have locked up complete supply chains, starving competitors? When Apple forced their book pricing model, it forced prices up at Amazon as well. When Apple limits or taxes competitors on the iOS platform, users who usually have no idea of this behavior will naturally migrate to Apple's solution because it provides just that much easier usability (geez why can't I buy that book I want in the Kindle app...oh well, here it is in the App Store). They are using their influence and control of that high-margin device that you paid for to build dominance in their other products. Not illegal or even immoral, but it eventually impacts everyone.

Also, exerting significant control over the rest of the market of smartphones still doesn't mean Apple has forced you to buy their products. Just means they are the leader in their particular market. you don't have to buy ANY smartphone or start a business based upon smartphones. Not sure how this is a violation of anybody's rights.