No offence taken, we are all students :) Monopolies (and duopolies, where there is collusion) can be bad for society, which is why we have specific exceptions in law to deal with them. Apple doesn’t hold a monopoly position in the smartphone market. In fact, they don’t even hold a majority position in the smartphone market. This is like going after Dr Pepper with antitrust...it’s never going to happen.
Thanks for the link, that is a good resource. I was wrong about them having a minority market share in the U.S., they’re more popular than I thought! They are still far from a monopoly position. Looks like it’s a roughly 70/30 split globally, though that’s not relevant for U.S. antitrust law (may be more relevant in Europe).