According to whom? I'm not a big Microsoft fan. Bill Gates was targeted by The Clinton administration because he wouldn't pay blackmail money to the troll. I'd vote for Steve Forbes for president but not Bill Gates so your argument lacks merit.
Having said that that, I respect Gates for living the capitalist dream. You seem to have a problem with that.
You highlighted monopolist and asked according to whom?
I assume you are familar with the finding, the appellate finding, and the review finding (by three different bench's) that Microsoft is a monoply and did unlawfully abuse it's monoply power. I believe I can still find and post links for you if you need them. Some 29 states attorneys for several years have been making that case, which the DOJ did finally pick up, but the DOJ wasn't leading, they were somewhat dragged into it by the states. A couple EU countries now also have similar suits pending, clearly in which the DOJ is not involved.
Bill Gates wanted Microsoft to be a monoply, again there many articles and books and detailing his drive to be number 1 and eliminate all competition. Nothing wrong with that, I had a similar goal at one time, and to that extent he is 'living the capitalist dream', to his credit.
My point was that a person who would unlawfully abuse their power (monopoly power in Gate's case) for their own self-serving ends (which is ok for a capitalist) would do the same as President. But that as President, abuse of power for self-serving purposes is harmful to citizens, and as I had assumed (as explained above) you'd vote for Gates as President, I asked why would you do that? Well you've clarified you wouldn't want him as president.
But I don't have a problem with him as a capitalist or a monopolist, provided he/Microsoft obeys the law.