The market selected MS to establish the monopoly. Why complain now?

The market didn't really select Microsoft to be a monopoly. In reality, a large portion of Microsoft's success can be attributed to simply being in the right place at the right time. They received the contract for the OS on the first IBM PCs, because an IBM executive was a friend with Bill Gates's mother. Once there, they jointly worked with IBM on the development of OS/2, promoting it publicly to both IBM and various third party application developers. Privately, Microsoft developed Windows and began developing their own applications for it. When the rift between the companies became evident, MS put all of its efforts behind Windows, leaving OS/2 to be developed further by IBM. At this stage, the two OSes were indeed competitors. IBM's OS/2 had the backing of third-party developers, while
Microsoft had a lead developing its own apps for Windows. This is where IBM failed. Weighed down by its own antitrust investigations, a nightmarish internal bureaucracy, executive leadership that still didn't acknowledge the viability of the PC over big iron, and a variety of marketing missteps, IBM allowed Microsoft to garner pivotal contracts with OEMs to distribute Windows over OS/2. You could go into a store and buy an OS/2 machine, but they were in a distinct minority compared to Windows machines.

The public, generally naive and often apprehensive, about personal computers became acclimated to the Windows OS due to sheer availability. It's what came on the PC, and most people were scared to hit the Enter key at most points, much less switch out an entire OS. This is true despite the fact that the OS/2 OS was universally regarded in the industry as being technically superior to Windows in every respect, including usability. Anyone who ever compared OS/2 2.1 to Windows 3.1 would have difficulty arguing this point. This is how an effective marketing plan and licensing agreements can make the difference for an inferior product.

Now, as with most things in life, once people become accustomed to the particular attributes of a given product, it is difficult, if not impossible, to convince them to even try, much less switch, to a competing product. Microsoft knows this foible of human nature and exploits it to its fullest extent. In fact, the only way to convince the average person to switch products is to make the competing product readily available to the consumer to enable them to make side-by-side comparisons. Then, and only then, can you hope to convert a consumer to the competing product, and then it is likely that only a small number will switch. Microsoft's licensing practices have made such a consumer choice impossible. A consumer cannot make a choice if they are unaware that alternatives even exist. This is how Microsoft has garnered and maintained its monopoly.

The ironic thing about this argument is that it is moot. Regardless of whether "the market" provided MS with its monopoly or whether MS obtained it through illegal means is immaterial. The conclusion remains the same, they are a monopoly, and, as such, are subject to a higher standard of business conduct.

Microsoft strives diligently to be a monopoly. They should. Every company should. Yet, when they attain that lofty goal, they deny it vehemently. Why? Why deny a reward that you have worked so hard to obtain? Because, legally, a monopoly is held to a code of conduct that Microsoft cannot attain. It is beyond their reach. Consequently, as with most things, Microsoft desires to "have their cake and eat it too". They want the market monopoly, but they do not want the legal monopoly designation. However, one does indeed go with the other.