Ideal money is not something that just holds its value over time. Money is ultimately a signalling system. Like the nervous system it's function is to coordinate independent actors directing their activity appropriately across the fitness landscape of the world and the economy.
The nervous system more like point-to-point communications - phone calls and text messages; directing moreso than signaling. An alternate analogy to the financial aspect might be the endocrine system which, among other things, regulates various hormone levels. Its effects are not as immediate as the nervous system, and the complex processes can be excruciatingly difficult to tease apart.
The Byzantine
coagulation cascade is a perfect example of such intricate signaling. Perhaps this is why trading and financial analysis are so difficult to pin down.
If we imposed a system like bitcoin upon a society with growth potential people would still invest, but they would not invest appropriately in response to economic opportunities. They would under-invest because a fixed supply of money creates a strong incentive against risk. With an utterly fixed money supply you receive a percentage of future economic growth simply by doing nothing. Only the most promising growth opportunities would receive investment and those with more marginal returns would be ignored. A bitcoin monetary system thus creates a strong vector against growth or in bitcoin lingo a HODL mentality.
This holds true to varying degrees until the system is sufficiently mature. At that point a fixed money supply will grow in value relative to the economy as a whole, albeit with a lag. There is no need for the money supply to dynamically adjust itself - a static supply takes care of a myriad of problems, but there are other considerations that arise.
Assume Bitcoin is the global currency and the global economy grows at 5% during a given year. The value of a Bitcoin should rise by about 5% overall. Some sectors of the economy will grow faster than that rate, others more slowly, and some may contract. Investment occurs when there is an expectation of return greater than can be obtained by other methods, so a startup generating 10% profit will be a better option than simply holding Bitcoin.
What becomes a problem is availability of the usable money supply. That's the stage when smaller denominations are used and the decimal moves to the left (smaller fractions) instead of the right (larger denominations). Long-term holders of Bitcoin who have savings that need not be actively utilized effectively centralize ownership of the units. Whether this is good or bad is another question.