If that were the case, thousands of people with bill gates's wealth, either you would have an accumulation of capital at the top that would be unsustainable, or more likely such a devaluation of the currency that having a hundred billion dollars wouldn't make you rich, think Zimbabwe.
That just assumes that accumulation of wealth is necessarily due to extracting it from the general economy rather than by generating wealth for the economy at large. Without debating the relative merits of Microsoft's contributions in particular, and assuming you accept the capitalist premise that someone can deserve to become wealthy by generating more wealth for society than they take home for their own benefit, why should there some intrinsic limit to how many people that can be true of or of how much value they can collectively create?
The problem is simply that we can't all be rich. We can all be billionaires, but we can't all be rich. The intrinsic limit comes from the fact that wealth itself is relative.
Using your example, Microsoft's creation of value to such a large consumer base couldn't have happened if there had been thousands of Microsofts equally successful (e.g. not thousands of companies can have a 90% market share in the same market at the same time, for company A to have 90% of market share of a market it means company B doesn't have it. Opportunity cost).
When you have thousands of people at the very very very top (.0001% cf 1%) that thousand of people would have to either extract wealth (not value, that's different) from the rest of the economy. There is only so much wealth to go around, regardless of how you represent it, whether its US Dollars or Friedman's island's stone money. Accumulation of wealth is relative.
When quality of life is taken into consideration, especially against most of human history and large portions of the world today, then I'd say most of the first world is already 'rich', we just aren't billionaires.
