@fillippone thanks for the serious response.

In the time series analysis, you can divide the period into (1) in-sample period and (2) post-sample or out-of-sample period. I have no problem with the (1) in-sample period if the model is statistically significant. In this case, the Stock To Flow Model can be presented and discussed to underline the scarcity, halvings, as you said, but only for 2009 - present (up to the model generated).

This post https://bitcointalk.org/index.php?topic=5191012.msg52693516#msg52693516 also about the in-sample period or in-sample forecast.

For forecasting (let's say 2020 or 2025), we deal with (2) the post-sample period. This is when "uncertainties" come to play. If every relationship stays the same, we can expect that this model can accurately predict future BTC prices. However, in economics, that's not possible since the world is continuously changing.

Suggested reading:
https://stats.stackexchange.com/questions/260899/what-is-difference-between-in-sample-and-out-of-sample-forecasts
https://people.duke.edu/~rnau/three.htm