The reason is simple. I feel the supply of Bitcoin at pegged 21m will be too limited for the global economy.
There is around $37 trillion in narrow money.
There is around $73 trillion in all stock markets combined.
There is around $90 trillion in broad money.
There is around $0.5 - 1 quadrillion in derivatives.
If we ever reached the point of 1 sat = 1 dollar, then 21 million bitcoin would be worth 2.1 quadrillion dollars, more than enough to cover every market in the world and then some. If you still think 21 million isn't enough, then a far better option to increasing the market cap is to subdivide it further. Lightning Network already works in milli-satoshi.
Fine analysis indeed.
But let me continue with your manner of economic analysis.
Here is what's Sotoshi Nakamoto want to achieve with a fixed bitcoin supply of 21m. He want become to be scarce asset.
Its based on the theory of Relative Scarcity of money.
Let me show your by example the difference between relative scarcity and extreme scarcity.
1.21m of bitcoin in circulation can be termed as extreme scarcity.
2.30m of bitcoin in circulation can be termed as relative scarcity.
While the former is too hard to make the latter is hard to make.
I feel bitcoin is better when its hard to make and not too hard to make.