I really don't want to defend Microsoft, but Internet Explorer won all that market share because back in the day IExplorer really was the best browser available. And given what happened next, I'm actually grateful for the IExplorer monopoly, because Firefox wouldn't have happened otherwise.

We tend to forget that even natural monopolies can be broken by new technology and innovation. And even big companies can be beaten by smaller ones. Microsoft tried to beat Google at search while Google was smaller and much less powerful than it is today. They couldn't, because big companies have a priority to protect their cash cows and don't necessarily have the talent or the focus required to tackle new markets (i.e. the innovator's dilemma). Google tried to beat Facebook at social. They also failed by being too conservative, while at the same time fucking their users. Can you spot a pattern?