[onebigbug]

You haven't listed all the possible options for obtaining a monopoly, though, including the one Microsoft was convicted of. In addition to creating a better product and by controlling the government, you can also engage in tying, whereby you have a monopoly (perhaps rightfully gained through innovation) and use it to gain a monopoly in another area by forcing customers to buy both together, you can sell at a loss until your competitors go out of business and then raise the price, you can collude with other companies to fix prices, or to only service certain areas or sectors.

Having a monopoly is not illegal, exploiting your position as a monopoly to maintain it is. That is what Microsoft did.