We can split hairs on definitions as long as you like. The trading desk I used to work at, we used to even have the phrase ponzi asset. It is quite common for firms in trouble to pay large dividends, to improve the stock rating, so they can raise more money. I worked on an equity derivs desk and have been corrupted by their terminology and no doubt thinking. I hope I made clear what I consider to be the issues, that lead me to want to use a negative word.

>as the market for Bitcoin has grown it has become less volatile.

I do not agree, the vomma does not show this characteristic trending in a reliable fashion.