Microsoft is somewhat of a special case, because they release a product that independent software developers need to code around. Most industries have business models that are much more open to competition than the operating systems sector.
To give an analogy:
Let's say that that Microsoft copyrighted and patented design of an electrical outlet a thousand times over. Originally, this particular electrical outlet gained market dominance because it was simply better than all of the others, and over the past couple decades, the overwhelming majority of electrical appliances have been created with plugs that interface with this outlet.
Now that Microsoft's outlet has become so ubiquitous, it has begun to overcharge for its electrical sockets.
Because of government, nobody else is allowed to make a carbon copy or even to use certain methods of copying the internal design to make their own (either to sell or to use for their own purposes). Furthermore, nobody outside of Microsoft even knows how it exactly works, so it's a very difficult reverse engineering prospect (don't ask me how people wouldn't know how an outlet works - suspend your disbelief for the analogy

). However, its much cheaper and arguably better competitors are having a lot of difficulty breaking into the market, because all existing appliances are made to interface with Microsoft's outlet! Sure, appliance manufacturers could make products with both plugs, and some do, but for most, it's just not cost-effective. Consumers, on the other hand, need to start seeing more appliances that use the new socket before it's worth the cost of time, energy, etc. to switch over. In other words, the advantages to Microsoft's product are not inherent to the product itself, but rather, they're just side effects of preexisting market dominance. It's competitors are fighting an uphill battle. One has found a niche with people who just LOOOOOVE electrical sockets, and the other has found a niche with people through snob appeal. However, neither are finding much traction with the mainstream consumer, no matter how much they dislike the cost of Microsoft's outlet or how often it malfunctions. Microsoft's competitors are slowly gaining market share, but it is an uphill battle that will last for many more years.
In other words, Microsoft's near-monopoly is no longer beneficial for the consumer, but because of copyright, patents, and the relatively unique nature of their industry (the fact that other software is built around the operating system), they still hold a position of market dominance.