Without any regulations/enforcement, monopoly is the one sure outcome
Incorrect. The only sure outcome is that the outcome is a transitory effect. Market share is not a horserace which has a defined beginning and end. It is an ongoing state of flux.
Microsoft is as big and dominant as it is becuase of certain regulations that free them of certain risks. The corporation is a fiction of government that eliminates what are otherwise limiting risks.
You really should do some real research on the history of monopolies. You'll find that a) they nearly always get that way through government assistance and b) by the time the government gets around to "doing something" it is usually too late - the fall has begun. Thus, the government was party to the problem, and claims to be a party to the solution when in fact it was irrelevant and at the party next door.