That number seems completely arbitrary. Why not $10 trillion or $1 quadrillion?

Because, as can be seen in the chart, during the desktop era, Microsoft grew at 60% per year.

Growing at 60% per year for ten years is a factor of slightly over 100.

Microsoft's overall value was also much more tied to their performance in the desktop market. The whole company can grow at 60% yoy if 60% of the company doubles in value. AI is not bringing them any revenue, and double nothing is still nothing.

There is only $500T wealth in the entire world. You're saying in 10 years, Microsoft will be worth 15-20% of the entire world?!

I did not make any prediction. I made a calculation. About the market cap of MS if it grows into the AI era as fast as it grew into the Desktop era.

You seem to assume that the global wealth is static. If that is the case, how were those $500T created in the first place?

It's not static, global wealth been growing at 3.8% per year for the past 25 years, which is historically quite a high rate. 10 more years at that rate would be 50% growth, or $750T.

The numbers you're talking about aren't feasible. MSFT grew that fast into the Desktop era because it was starting from a much smaller number. You can grow from $400m to $40b, but you growing from $40b to $4T is a much different story (and remarkable that they were able to do that!). Growing from $4T to $100T is not only unprecedented but unimaginable.

So you might be making a calculation instead of a prediction, but it's a worthless calculation. You may as well extrapolate the 10x weight gain of an infant to an adult and calculate that their weight at middle-age will be 1000 pounds.