1) This is the formula for my "downward volatility" , i dont know exactly the term for it, but if you calculate this, you will get that value, which will then show you the volatility of only the down movements, which should give you a risk understanding of bitcoin price crashes, because price increase doesnt matter, that is beneficial.
This is a formula for calculating standard deviation. But it makes no sense in the way you use it (that most likely explains the reason why you don't know a name for it), since when calculating an average for x, you use all values...
Your "only downward volatility" by implication includes "upward volatility" as well
No it doesnt. This is the formula which gives you the "relative downward volatility" to be more precise. Yes you need the upward values to calculate them mean, but that is neutral.
So you only look for the downward volatility, relative to the mean, that is a more precise definition.
It does make sense and it has pretty good statistical significance.
Could you please provide external references showing this notion usefulness (for anything)? I think you will have a hard time explaining why you use an average value to calculate what you call "downward volatility", since it will be meaningless (whether you like it or not) if the price moves all way up while you would still get some pretty high positive value for your "downward volatility" when it evidently should be equal to 0. I guess you should use the mean of all downward price movements to reach where you aim at. It seems more logical and viable in regards to your idea of "downward volatility"...
And I'm curious if you understand what "statistical significance" actually means
Hmm maybe you have a point there about the mean of downward movements. I completely forgot to check that out.
Yes i know what statistical significance means.
I prefer water and food before that both..... 
Well... taking in to account the fact that an average human being requires 0.2 cubic meters of water every day, you might need to store some 14,600 cubic meters of water, if you want a family to survive for 50 years without any supplies from outside. It will require a lot of space. And the case with food is even more trickier. Most of the food items will get damaged after 6 or 7 months. How will you store them?
Canned meat can be stored a few dozen years. But I guess if that was a question, you should better care for the safety and preservation of your ammo...
Yes but you want a very value-dense material, in the sense of most value / less volume (m^3)
So the best thing for that is diamonds, not gold. Diamonds have the most value / less volume, so i dont understand why you go with gold.
If we go with "materialism", then obviously diamonds are far superior store of value to gold.
But we want to go with intangible things, because any material stuff can be easily stolen by a burglar.
Thus bitcoin is superior to: platinum,gold,silver,diamonds, emeralds,etc