Should we use gold to predict Nasdaq?
Not exclusively. As mentioned, both the structure and the function of the two assets are different. It's like trying to equate stocks with bonds - trying to value one using techniques that are effective for the other generally ends up with results that don't make sense. Bitcoin and gold are functionally
equivalent, even though their structures are different.
Given circumstance/input A:
Stocks behave in pattern A
Bonds behave in pattern B
Gold behaves in pattern C
Given circumstance/input B:
Stocks behave in pattern B
Bonds behave in pattern C
Gold behaves in pattern A
And so on for input C, D, etc...
Each asset class responds in a different way to various events and situations, which is why they rise and fall at disparate times. Since Bitcoin is functionally equivalent to gold, it is reasonable to expect it to behave similarly with the same inputs. In the above examples, pattern A occurred in both stocks and gold, but were dependent upon different inputs.
What may be possible is observing whether input B frequently follows input A. Then a pattern A in seen the NASDAQ might be forthcoming in gold if
there are signs of input B. A 50,000 ft overview would be of historical currency debasement/inflation - the pattern has occurred so often through the ages that the current similarities are very likely to eventually lead to what has happened in the past.
Coming back to Bitcoin, there is a question of magnitude. Because Bitcoin is a micro-economy, any adoption will cause its growth to be much greater than gold; that means the time-frame will be compressed - it's possible to see 100 years of gold's growth in 100 weeks. In addition, similar patterns are occurring at the same time
- makes sense because of the functional equivalency between gold and Bitcoin. That accelerated, exponential growth would also occur synchronously in a hypothetical stock exchange 1% the size of NASDAQ, as long as the two work in a similar fashion.
One thing to keep in mind is that Bitcoin is mostly growing as a transactional medium right now, rather than a store of value like gold is today. The former is relatively unknown while the latter is familiar to everyone and has been for thousands of years. Bitcoin supply is also growing at ~25% annually; gold supply increases at ~1.5% per year. These are the factors that introduce some divergence, but they're still similar enough to be highly correlated.
Always consider which asset class best describes the item in question: commodity, equity share, contract, currency, etc. Everything else tends to fall into place after that.
tl;dr comparing apples to oranges is still comparing fruit - comparing apples to steel is completely different.